What is the difference between a mineral and a rock? A rock is an aggregate or mix, of one or more minerals. Here are some fun facts about minerals to enjoy…

René Just Haüy

2022 was the bicentennial of the death of René Just Haüy (2/28/1743 – 6/3/1822). Not a name many of us know, but Haüy was a French mineralogist and is important because he is known as the Father of Modern Crystallography. He studied crystal structure, applied his theories to mineral classification and wrote several books including the Traité de Minéralogie.

To honor him and the importance of minerals in our world, the International Mineralogical Association named 2022 the Year of Mineralogy.

What are Mineralogy & Crystallography?

Mineralogy is the study of everything about minerals including their crystal structure, physical and chemical properties. Crystallography is the study of the structure and properties of crystals.

How Minerals Are Formed

Minerals are formed in four main ways:

• From Magma – Hot, molten lava cools and crystallizes to form minerals such as topaz.
• From Water – Chemicals in saturated water precipitate, or separate, into solids. An easy example is salt, halite, that’s left behind after ocean water evaporates.
• Alteration – As minerals react, slowly or quickly, with their environment they form different minerals. Cuprite forms when it’s exposed to oxygen.
• Metamorphism – Exposure to heat and pressure alters the chemistry of a mineral to become a different mineral such as rubies.

Glorious Gemstones

Gemstones used for jewelry can be considered at the top of the mineral world. They are rare, valuable, popular and prized for their mineral colors which can be quite vivid once they are cut and polished.

FYI – Not all gemstones come from minerals, for example, pearls and amber. Gems can be precious meaning they are the rarest and most valuable. There are only four precious gems; diamonds, rubies, emeralds and sapphires. Gems that are also popular for jewelry but not as rare are called semiprecious…think amethyst, agate and turquoise.

The rating of precious or semiprecious was made long ago. Today, some semiprecious stones can be worth more than precious stones. Also, it doesn’t take into account scientific classifications of minerals. For example, emeralds are a type of beryl. Aquamarines are also a type of beryl.

Fabulous Diamonds

The word diamond comes from the Greek word adamas which means “invincible.” That’s certainly an accurate description given that diamonds have a Mohs hardness of ten!

According to National Geographic Kids Weird but True Rocks & Minerals, “On Earth’s surface, diamonds are rare. But go down around 100 miles below the surface and it’s a different story. Some scientists have estimated there may be more than a quadrillion tons of diamonds locked in rocks in Earth’s interior.”

This story about celebrating minerals appeared in Rock & Gem magazine. Click here to subscribe. Story by Pam Freeman.

The post Celebrating Minerals first appeared on Rock & Gem Magazine.

Sapphire

One of the official state gemstones of Montana, sapphires hold a special place in the Treasure State where they are readily found. Sapphires and rubies are both corundum, an aluminum oxide mineral typically found in crystalline form. The only difference between the two is the presence of chromium. If the corundum is red, it’s ruby. Otherwise, it’s always a sapphire.

One of the most desired types of gemstones, the most well-known sapphire hue is deep blue, but these gemstones are found in pink, green, violet, orange, purple and even brown. When they’re not blue, they’re referred to as fancy sapphires. These colors are because of the varying degrees of chromium, titanium oxide and iron within the stones. Sapphires also possess a trait called asterism where needle-like inclusions create the appearance of a six or twelve-patterned star. Beyond this unique characteristic appreciated by faceters, sapphires have a Mohs Amy Grisak; Getty Images/Science Photo Library value of nine, just below a diamond, making them extremely durable and an excellent choice for jewelry.

Tiger’s Eye

This distinct gem has a long history of fending off the “evil eye,” with its resemblance to a cat’s eye. In gemology, this trait is called chatoyancy, a French term meaning “shining like a cat’s eye.” When there are crocidolite (blue asbestos) fibers within cabochon-cut gemstones running parallel to each other, the rounded surface allows the light to reflect in a way that gives the tiger’s eye its signature look. Originally, scientists thought this phenomenon occurred when the crocidolite within the stone was changed by iron oxide and replaced with silica. But even though the coloration comes from this process, some researchers believe it’s actually crocidolite inclusions within columns of quartz within the stone that form the distinct paralleling nature.

Regardless of how it formed, tiger’s eye is a favorite gem for tumbling and with a Mohs value of seven, it’s a versatile stone for a multitude of uses. While it’s a ubiquitous stone these days, in the 1870s a single carat of tiger’s eye was worth an ounce of gold.

Unakite

Unakite is a terrific example of when a gemstone is a true rock as this beautiful pink and green specimen is a composite of metamorphic rocks including orthoclase, epidote and milky quartz. It’s formed during hydrothermal metamorphosis when the epidote replaces the silicate minerals, primarily plagioclase, within the granite. The epidote is green within unakite, while the pink orthoclase feldspar and quartz create the colorful speckling.

First found in the Unakas Mountains of Western North Carolina and Eastern Tennessee, it’s sometimes found in the rivers of the region, along with the beaches of Lake Superior where glaciers deposited the metamorphic rocks. With a Mohs rating of six to seven, unakite is among the types of gemstones that tumble well. It has been used to make small sculptures or is cut for jewelry. As eye-catching as it is, unakite is also valuable in construction on many levels, including being used as trim along the front steps of the south entrance of the Smithsonian National Museum of Natural History. It is also sometimes used less visibly as crushed stone in highway construction.

Vesuvianite

Sometimes called idocrase, vesuvianite was originally found along Mount Vesuvius in Italy, which buried the nearby inhabitants of the city of Vesuvius on August 24 in 79 AD, ironically during the festival of Vulcanalia, the god of fire. In the world of gem cutting, vesuvianite often refers to the rough stone, while the faceted gems are called idocrase.

Regardless of the name, this is a calcium-aluminum-silicate mineral that forms in a tetragonal structure. Its most popular colorations range from yellowish green to brownish or olive green, although there is a blue version called cyprine that derives its color from trace amounts of copper. With a Mohs value of six, vesuvianite isn’t a very hard stone and is often used for larger jewelry and sculptures. In its green coloration, it’s sometimes mistaken for other types of gemstones like peridot, although vesuvianite is far rarer.

White Topaz

While topaz is found in practically the entire color range, the white topaz is the clear version and boasts a similar appearance to a diamond. Outside of cost, there are distinct differences between the two types of gemstones. Topazes and diamonds are closely alike in clarity and color, but brilliance is where diamonds shine. Hardness is another determining factor. Diamonds reign supreme rating at Mohs 10, while topazes register as a Mohs eight, considerably less durable with a greater risk of scratching.

Topaz is created when water and magma react during the metamorphic process creating pegmatite featuring natural topaz that is typically initially clear. While the wide variety of colors is because of impurities, such as chromium replacing the aluminum within the stone, white topaz is the gem in its purest form. Specific hues are also created with heat, irradiation or the application of metal oxides to enhance colors. Topaz also exhibits pleochroism where the gem exhibits different colors depending on its angle, although the white topaz tends to remain consistent in its coloration.

Xenotime

On occasion, there are types of gemstones cut from this rare earth mineral, often found in yellowish-orange to reddish-brown hues, although high enough quality stones to facet are rare.

Like topaz, xenotime is found in pegmatite formations, as well as igneous rock and gneiss. Uranium and thorium are often found within this stone, creating natural radioactivity, although it is more commonly seen as a source for the transition metal yttrium, which is used as an alloy in the production of camera lenses and lasers. Its name is derived from the Greek terms for “vain” and “honor” in an early scientist’s snarky rebuke of another. Initially, Swedish chemist Jöns Jacob Berzelius believed he discovered a new element within the xenotime. This turned out to be the already known yttrium, which prompted mineralogist François Sulpice Beudant to throw down a bit of shade on the claim.

Yellow Kunzite

True gemologists might shudder at the inclusion of yellow kunzite in this types of gemstones list, but it’s an example of when marketing can be misguided. As a rule, kunzite is a pink to light purple variety of spodumene, a lithium-rich mineral found, once again, in pegmatite formations. Manganese gives kunzite those attractive colors. When the gem is yellow, it’s typically just called yellow spodumene. The name change might be a matter of one word sounding more appealing than the other, but it is still misleading as kunzite implies a specific hue. With a Mohs value of six and a half to seven, it is not a very durable gemstone, but it’s possible to find specimens of 20 carats or more. Spodumene, in general, is an important source of lithium, which is critical for car batteries, phones and medicine. It is mined in Afghanistan, Pakistan, California, North Carolina and South Dakota.

Zircon

Not to be confused with the synthetic cubic zirconia, zircon earned its place as a popular gemstone 2000 years ago. Found in sand and as part of many of the rocks throughout the world, zircon is one of the oldest minerals on earth. Because of its uranium content, scientists in Australia dated it back 4.4 million years. Not all zircons are radioactive, but those that are can be heat-treated to stabilize the integrity of the stone by slowing the degradation of the crystalline structure. In their natural form, zircons are found in colors ranging from clear to yellow, green, purple, brown and grays, which are typically caused because of radiation or impurities. Blue zircons, which have been popular since Victorian times, are created through heat treatments.

This story about types of gemstones by letter appeared in Rock & Gem magazine. Click here to subscribe. Story by Amy Grisak.

The post Types of Gemstones By Letter (S-Z) first appeared on Rock & Gem Magazine.

This is the first in a three-part series also covering types of gemstones with the letters J to R and types of gemstones with the letters S to Z.

What is a Gemstone? The definition of a gemstone isn’t quite as precise as the faceted beauties it describes. In general, when minerals, and sometimes organic materials such as amber, are cut and polished to create jewelry, we call them gemstones. There are nuances and outliers because some types of gemstones are too delicate to be worn, but most people in the gem world accept this general concept. To further clarify, types of gemstones are divided into “precious and semi-precious” stones with only diamonds, emeralds, sapphires and rubies encompassing the precious category. Everything else falls into the semi-precious zone, although this doesn’t necessarily imply inherent modern value or desirable characteristics. Regardless of the classification, there’s no question that when we can bring out the inherent beauty within these stones, it is something to be truly prized.

Agate

Agate is a silica-based mineral and is a popular semiprecious stone because of its attractive coloration and banding. Reportedly discovered by Greek philosopher Theophrastus roughly 2500 years ago, early people throughout the Middle East, Russia, and Greece used agates to create ornaments. According to research by the Bureau of American Ethnology, Indigenous People utilized them in much the same way.

Agate is a chalcedony, which is a type of cryptocrystalline quartz. Like many stones in this category, it’s created when groundwater seeps into the igneous rock where silica deposits form concentric layers within the rock cavities and crevices to create the telltale banded patterns.

The wide variety of colors, ranging from brown, black, white, red, gray, pink and yellow, are because of impurities in the groundwater. With a seven on the Mohs rating, agates are on the upper end of the hardness scale. This makes this translucent stone a favorite for rock tumbling. It’s often used for jewelry as well.

Bloodstone

An opaque, dark green type of gemstone, bloodstone features distinctive orange to scarlet red splatters that look like blood at first glance. This is the telltale signature of this traditional birthstone for March. The more modern birthstone choice is aquamarine.

Bloodstone is also called heliotrope, a name derived from the Greek helio meaning sun and tropos meaning toward the sun. If you garden, you’re familiar with heliotrope plants that turn toward the sun as they grow. This name indicates how the stone reflects the light. Along with legends of healing powers, bloodstone is also known as a protective stone. People will often wear or carry bloodstones to keep threats at bay.

The minerals chlorite and amphibole are responsible for the deep green coloration while iron oxide inclusions create the blood-red speckling.

Carnelian

Carnelian is one of the least expensive chalcedonies, the translucent yellow-orange to rich amber or even reddish-brown gems darken when heat treated. This includes the heat of the sun, so it’s best to keep your stone out of the sun to keep the color true. Iron is responsible for the red coloration and it’s what oxidizes and deepens when exposed to heat.

Carnelian is sometimes confused with jasper, although jasper is a type of gemstone that is typically a deep red and is opaque, rather than translucent. Plus, jasper often exhibits banding patterns on its surface appearance.

Carnelian is found throughout the world with some of the highest quality stones found in Scotland, Brazil and Washington State.

Even though it’s relatively inexpensive, many so-called carnelians are dyed and heat-treated agates. To determine if a carnelian is real, hold it up to the light. If it’s a natural carnelian, it looks cloudy. If it’s a heat-treated agate, it will most likely show striping.

Dumortierite

Although colors range from brown, green, and the rarer violet and pink, the eye-catching denim blue of this type of gemstone is probably the most popular with gemstone enthusiasts.

An aluminum boro-silicate mineral, dumortierite occurs in regions of high metamorphic activity that are also rich in aluminum and boron. Manganese, iron, and sometimes zinc inclusions, are responsible for the blue coloration.

Dumortierite was first described in 1881 after being found in the French Alps. It was named for the French paleontologist, Eugene Dumortier.

Dumortierite has a glassy (vitreous) luster. Its fibrous nature creates fine, almost hair-like radial crystals within the structure. The blue variation is sometimes mistaken for lapis lazuli, but dumortierite is typically a deeper blue or violet, plus lapis lazuli sports white or gold metallic flecks because of the pyrite within it.

Dumortierite quartz is quartz with inclusions of dumortierite.

Emerald

The birthstone for May, emeralds are a type of gemstone that earns their place as an adjective to describe a particularly intense green. The name is derived from the Greek word smaragdos, meaning green stone.

Created in metamorphic rocks when hot magma flowed over and through the crevices of limestone and shale, emeralds are a beryllium aluminum silicate. Although emeralds are a type of beryl, not all beryls are emeralds. While green beryl is still green, it’s distinctly lighter.

Chromium oxide is responsible for the emerald’s deep green. Other gems, such as peridot and tsavorite garnets, are also found in green hues but not with the same vibrancy. Registering 7-8.5 on the Mohs hardness scale and forming in hexagonal crystals, emeralds are long favorites for precious jewelry, but fakes abound. To determine authenticity, inspect the stone with a 10X loop. Flaws and inclusions, particularly a small crystal within the stone, indicate a natural emerald. Air bubbles or even a “too perfect” stone are tell-tale signs that it is not real.

Fluorite

Made of calcium fluoride, pure fluorite is colorless, yet samples are commonly found in shades of purple, golden-yellow, green, blue, pink and brown. These types of gemstones are translucent to nearly transparent with attractive banding. The term “fluorescence” became part of the terminology when physicist Sir George Gabriel Stokes was working with fluorite in 1852. Although fluorescence doesn’t consistently occur, fluorite is known to glow when there is the presence of uranium, yttrium and other rare earth elements. It often emits blue, although yellow, green, white and red shades are possible.

Also called fluorspar, it’s been produced in Illinois since the 1800s and is the state mineral. Often forming in cubic crystals, it is popular for jewelry but has a wide number of commercial applications ranging from an ingredient in ceramics to a flux used in refining metals.

Garnet

Many people picture garnets as red stones, but these types of gemstones are also found in shades of orange, pinkish-orange, green, reddish-purple, colorless and even blue and green, albeit these last two are rarer.

Garnets are formed when aluminum-laden sedimentary rock is metamorphosed. Garnets are one of the most widespread types of gemstones throughout the world. While the bulk of garnets is mined for industrial applications, it’s one of the oldest known gemstones and has been used for ornamental purposes for 5000 years. Historical evidence shows stones within the necklaces of pharaohs. Garnet signet rings were used by Roman leaders to seal documents.

Sometimes mistaken for a ruby, garnets are usually a darker red with brownish tones. When it’s held up to the light, yellow bands are often visible in a garnet while a ruby will be clear.

Hematite

Consisting of 70 percent iron, hematite is one of the primary ores of iron. Fortunately, it is one of the most abundant minerals on Earth. According to NASA, it’s also the most abundant mineral on Mars. The iron-rich environment is why Mars is dubbed the “red planet.”

Named as far back as 300-325 BCE, hematite is derived from the Greek haima, meaning blood. These types of gemstones are found in colors ranging from rust-red, brown, steel-gray to black, it always leaves a red streak when scratched on a scratchpad.

The distinct reddish hue has been used in artwork from the earliest cave paintings. It was a key pigment for Renaissance artists creating paintings with canvas and oil in the Middle Ages. Besides its importance as an ore for iron and in art, it effectively stops radiation making it useful in shielding applications. Plus, it creates a beautiful tumbled stone for those who love to collect them.

Iolite

This beautiful violet-blue stone was the secret to the Vikings’ success in crossing the ocean as they looked through a thin iolite specimen to determine the position of the sun on cloudy days. The key to this unique quality is called pleochroism where different colors are visible at different angles. For example, a piece of iolite may have the classic violet-blue hue on one side, but when it’s turned over, it appears yellow or clear.

A silicate of aluminum, iron and magnesium, iolite (also known as the mineral cordierite) is created in metamorphic and igneous rock formations. Derived from the Greek word ios meaning violet, some iolite is blue enough to look like a sapphire. Some speculate this quality is because of the presence of titanium, although iolites are easily distinguishable because of pleochroism.

This story about types of gemstones appeared in Rock & Gem magazine. Click here to subscribe. Story by Amy Grisak.

The post Types of Gemstones By Letter (A-I) first appeared on Rock & Gem Magazine.

Jasper

Jasper is found throughout the world. This chalcedony is a cryptocrystalline form of silica. Jasper types of gemstones come in colors ranging from green, red, blue, orange, yellow and brown. The colors are because of impurities such as ash, clay or minerals within the stones. Iron typically creates the reddish hues, while manganese oxide is responsible for blues, and inclusions of iron oxide or the mineral goethite create the yellows.

Many times there are types of gemstones with examples of various inclusions, such as with the bloodstone jasper, where chlorite and pyroxene cause the deep green, while iron is responsible for the red speckling. Jasper’s name is based on the French word “jaspre” which came from the Latin “jaspidem” meaning “speckled stone.” This is fitting because when polished, jasper has a speckled pattern seemingly just below the surface.

Kunzite

The best-known variety of spodumene, kunzite is the pink to purple version of this important mineral that is still sometimes mined for lithium production. Kunzite boasts beautiful pink or purplish hues because of the presence of manganese, while chromium creates the greens of another variety, hiddenite.

A fascinating aspect of kunzite is its pleochroic attributes where it displays different colors, such as a combination of pink, purple and transparent, depending on which way you look through the crystal. This is a key consideration when cutting the gem. It also has phosphorescence, which allows the stone to absorb light and then release it in the dark, as with any of our favorite glow-in-the-dark items. The drawback is excessive exposure to sunlight fades its beautiful colors.

With a Mohs rating of 7, eye-catching colors, and the unique characteristics of pleochroism and phosphorescence, it’s even more intriguing to know that large crystals are possible with the best example being an 880-carat heart-shaped kunzite housed at the Smithsonian.

Lapis Lazuli

The beautiful deep blue lapis lazuli is an example of when a gemstone is not a mineral. Instead, lapis lazuli is a rock consisting of multiple minerals, including lazurite, calcite, pyrite, afghanite and several others.

To be considered true lapis lazuli, the rock has to contain at least 25 percent of the mineral lazurite that lends to the distinct blue coloration. Calcite is usually the next most prevalent mineral which often shows up as white layers or mottling. Pyrite provides the shiny gold flecks in some specimens.

Afghanistan is the hotbed of lapis lazuli. There are records of it being mined in the Badakhshan Province of the northeastern part of the country as early as 7000 B.C. The name is derived from the Arabic word “lazaward” meaning “heaven” along with the Persian term for blue, “lazhuward.” In ancient times, Egyptian women also used powdered lapis as an eye shadow. And even in the 1800s, powdered lapis was used to create ultramarine blue paint used in oil canvas paintings, such as Vincent Van Gogh’s “The Starry Night.”

Malachite

A vibrant green gemstone with distinct parallel banding, malachite is a striking specimen and its popularity for thousands of years is no surprise. Derived from the Greek word meaning “mallows,” this correlates to the deep green of malachite with the color of the mallow plant’s leaves.

The gem color is derived from the copper carbonate hydroxide minerals often found in regions near copper deposits. Because malachite is a fairly malleable oxidized copper ore, it’s possible to extract copper from it using sulfuric acid.

The Egyptians also figured out how to remove the copper by placing powdered malachite in a hot fire, which resulted in tiny spheres of copper as a by-product. They used this copper to make cookware, and razors and eventually created stronger bronze by adding arsenic or tin. They also used finely ground gemstones as a distinctive eye paint. Besides adorning the appearance of ancient Egyptians, malachite is one of the oldest known pigments and was identified in the artwork of Egyptian tombs.

Natrolite

Typically found with slender, needle-like crystals protruding from the crystal, natrolite is an eye-catching specimen. It’s difficult to imagine such a fragile-looking stone cut and polished into impressively faceted gems, although high-quality gems are truly rare. Not surprisingly, it’s sometimes called needle stone.

Natrolite leans toward a colorless appearance but can be found in white, light yellow, green, orange, pink, brown or gray. When it’s placed under either longwave or shortwave ultraviolet light, it glows in yellow, orange and sometimes pale green.

A member of the zeolite group, which are hydrated aluminosilicate minerals, the name comes from the Greek words for soda and stone, “natron” and “lithos.” It was officially named by the German chemist Martin Heinrich Klaproth in the early 1800s. Natrolite is found in regions where there are veins of basaltic rocks, along with granite and the igneous rock, gneiss.

Onyx

While onyx and agate are both types of chalcedonies and share many similarities, one way to tell them apart is to look at their banding. Agate sports curved bands and onyx has straight, parallel banding. When many people envision onyx, they think of a black gem but is often found in red, brown or yellow, which is called sardonyx. Red and white layers are usually what is referred to as carnelian onyx, while Nicolo onyx has light blue layers alternating with black.

Since ancient times, artists have created intricately carved cameos. Black onyx grew in popularity during the Victorian Era when mourning jewelry was an integral part of society. After Queen Victoria’s husband Prince Albert passed away in 1861, she and all of the British Empire descended into mourning. Besides onyx, jet, vulcanite and even black enamel were used in the adornments. Many included personal mementos, such as hair, woven into the locket or watch fob.

Peridot

Peridot is the gem variety of the common mineral olivine and one with a unique origination story. Unlike many other minerals that form on the Earth’s surface, peridots are birthed either deep within the Earth’s upper mantle where they are brought to the surface through volcanic activity, or deposited by meteorites.

Because of this relationship with volcanoes, Hawaiian legend claims that peridot symbolizes the tears of Pele, the goddess of volcanoes and fire. It is so intertwined that there are several beaches on the island of Oahu that are made up of green sand that glitters with these tiny green crystals. Its distinct coloration is because of the percentage of iron in the formation of the crystals, yet can vary to the point where the stone looks more yellow, olive or even greenish-brown.

The ancient Egyptians referred to peridots as the “gem of the sun,” and some experts surmise that Cleopatra’s famed emeralds may have actually been peridot gemstones.

Quartz

Quartz might not only be one of the most abundant minerals found on Earth, but it is also possibly one of the most useful as it is found in everything from glass to electronics, and has been critical in the mining industry. One fascinating aspect of quartz crystals is their vibrational ability.

As a piezoelectric material, quartz creates an electrical charge when it’s squeezed. As a result, it vibrates 32,768 times per second, and for nearly a century, quartz crystals have been used in watches, computers, GPS units and a remarkable number of everyday items. Found in several varieties, types of gemstones include rosy quartz, smoky quartz and amethyst, quartz is as diverse as it is beautiful. The coloration differences are often due to natural radiation reacting with specific minerals within the quartz. For instance, iron is responsible for the purple hue of amethyst while aluminum creates the gray of the smoky quartz.

Ruby

The terms “ruby” and “red” are practically synonymous, or at the very least, ruby is often used as an adjective to describe types of gemstones with a particular shade of color. Its name comes from the Latin word for red, “ruber.” Bringing the highest per-carat price of any of the colored stones in the modern market, rubies shine among the corundums, which also include sapphires. Like sapphires, they score high on the Mohs scale ranking just below a diamond.

Pure corundums are colorless, but chromium causes the striking red coloration of rubies. The deeper the color, the more chromium is present. This element also causes rubies to glow under ultraviolet light. Because of rubies’ chemical composition, the first working laser, called the ruby laser, was created in 1960 by Theodore Maiman. One of its first uses was in range-finding equipment, but the technology is used to this day as a light source for medical procedures or high-speed photography.

As this list demonstrates, types of gemstones go well beyond only beautiful objects. The myriad of important day-to-day applications for gemstones gives us a deeper appreciation of what might be considered common gems.

This story about types of gemstones by letter appeared in Rock & Gem magazine. Click here to subscribe. Story by Amy Grisak.

The post Types of Gemstones by Letter (J-R) first appeared on Rock & Gem Magazine.

Identifying the Risks of Radioactive Minerals

Understanding which parts of your collection may pose a risk is the first step. You might have just a few individual, radioactive mineral specimens. But some large rocks may also contain an amalgamation of multiple types of potentially radioactive minerals. In addition to these radioactive minerals, there are also daughter products that are created as the result of radioactive decay. Daughter products, such as radium, radon gas and uranium, are themselves radioactive.

According to Alysson Rowan, author of Here Be Dragons or The Care and Feeding of Radioactive Mineral Species, some radioactive minerals may even be hiding in plain sight. “A specimen that doesn’t look very good because it’s not well crystalized — somebody may cut that into a decorative stone and mount it for wearing,” Rowan says. “You can find these things on sale, and there’s no mention of the fact that it is radioactive.”

Based in Holsworthy, England, Rowan is also a former radiation safety worker with extensive training in geology. She continues, “There’s no mention that this is not something that you would want to wear, so, people buy these things and wear them in ignorance.”

Detection Equipment

Because uranium minerals tend to be very colorful, they’re among the most popular with collectors. “The other thing is that there are a lot of them that are fluorescent,” Rowan says. “With uranium minerals, you tend to get greens and yellows, but there are minerals that glow blue, and red, and I think there’s even one that’s now known to fluoresce purple.”

Incidentally, to test the radioactivity of your stash, you’ll want to purchase a handheld radiation detector. “If they’re going somewhere to collect uranium minerals or they expect to find uranium minerals, a handheld ‘Geiger counter’ is a must-have,” Rowan suggests. “Of course, they’re not all Geiger counters now. . . . A lot of them are scintillators which are a lot more sensitive and a lot more durable. They generally show how much radiation they’re detecting either on a meter or on an alphanumeric display.”

You can also find used Geiger counters for sale online. “A lot of people buy them second-hand on eBay,” she says. “The American Civil Defense monitors are very, very popular because there’s a lot of them about.”

Saléeite and autunite are two colorful — and radioactive — minerals. “In bright sunlight, you can see the fluorescence,” Rowan notes. Both are in the bright yellow-green range.

Just don’t get too attached to that autunite, as it will literally disintegrate. “Autunite is what’s known as a metamict,” Rowan explains. “It decays radioactively, and the radiation damages the crystal. Inside a few years, it’s just a pile of dust. . . . And, so, autunite will actually spread all over the place.”

Radiation Effects

Containing that radioactive spread is paramount because the negative effects of radiation on the body are cumulative. In other words? The radiation you absorb builds up over time. You can inadvertently expose yourself to radiation internally by absorbing contaminants through your skin. You can also inhale or ingest radioactive contaminants.

The acute effects of radiation exposure can range from erythema — akin to a deep tissue sunburn — to renal failure. “The uranyl minerals—that is uranium oxide as a radical—are toxic to your kidneys,” Rowan says. “So, that is what you’ve got when you pick up most fluorescent minerals. It’s uranyl phosphates, uranyl nitrates—they are highly toxic.”

Over the long term, exposure to some radioactive compounds can even result in bone cancer and leukemia. In her book, Rowan writes, “Inhaled uranous and thorium compounds, and to a lesser extent the uranyl compounds will result in both toxic and radiation damage to the lung. Long-term effects will include bronchitic and emphysema-like symptoms as well as a range of pulmonary and pleural cancers.”

Smoke Alarm

Keeping cigarettes, incense, and other smoky stuff away from radioactive specimens is especially important.

For safety’s sake, you should never eat or drink while handling radioactive minerals. Applying a quick smidge of lip balm’s another no-no. And smoking is right out, too.

“The thing about smoking is one thing that you do is that you handle the rock and you put your cigarette to your mouth and you’ve immediately got rock dust on your lips,” says Alysson Rowan, the author of Here Be Dragons or The Care and Feeding of Radioactive Mineral Species.

What’s more, let’s say some of your specimens contain uranium. As uranium goes through its multiple stages of decay, it eventually releases radioactive radon daughter products and radon gas. “The airborne activity from radon daughters and radon gas itself will attach themselves to smoke,” Rowan continues. “So, when you re-inhale smoke, you’re inhaling the radioactive contaminants in the atmosphere.”

In her work, Rowan writes, “It has been noted that the presence of blue smoke from cigarettes (the plume that rises from the burning tobacco) collects the radioactive radon daughter products more surely than any other means of concentration. This means that the spent smoke you breathe in a high radon concentration area is bringing those radioactive materials into your lungs in a form which tends to remain inside your body.” Such radiation exposure in the human body is cumulative. Rather than dissipate, the radiation exposure adds up. “The consensus of scientific opinion is that a given dose from radon is possibly 10 or 15 times as dangerous to a smoker as to a nonsmoker,” Rowan notes. To mitigate this risk, never smoke in areas where you keep radioactive specimens.

Minimizing Exposure

Although different minerals pose differing degrees of risk, if you are pregnant, you should avoid contact with radioactive minerals altogether. As for young children? “Before puberty, we are a lot more susceptible to radiation damage because of the rapid cell division,” Rowan says. “Children should not be around. . . radioactive minerals more than absolutely necessary for their study.”

There are several precautions you can take to minimize your overall radiation exposure and still appreciate the radioactive specimens in your collection. Besides the degree to which a mineral is radioactive, the amount of the mineral in question matters as well as the cumulative amount of time that you spend in direct contact with it.

“If you sit with a pound of uraninite using it as a paperweight on your desk, that is going to give you a problem eventually,” Rowan maintains. “If, on the other hand, you have that pound of uraninite and it’s in a lead-acrylic case, that reduces the dose rate and, therefore, it’s not quite the same problem.”

Display Do’s and Don’ts

“You also have to take into account how far you are from that specimen,” Rowan adds.

When you increase the distance between yourself and the specimen, you decrease your potential radiation dose. Adding shielding materials like lead, wood or glass can further reduce your radiation exposure.

“For the most part, you put [your collection] on display in a cabinet,” she says. “The idea is that you’re keeping dust off of your specimens, but you’re keeping dust from the specimens fixed.”

Regarding those uranium-rich minerals, keep in mind that uranium decays into radium which, in turn, will decay into radon gas. Because this heavy, radioactive gas can easily migrate, you should air out your uranium mineral display cases periodically. “I’ve done this with my own cabinet,” Rowan says. “You open the cabinet and stick your [radiation] meter in and the radiation count goes up. And, over about half an hour, the count rate goes right down, because the radon daughters in there only have a short half-life.”

Still, she cautions, “If you’re a serious uranium collector, then it’s probably a good idea to have vented cabinets—venting to the outside world.”

Also, never store or display uranium minerals in a basement. “Radon gas is an awful lot denser than air,” Rowan explains. “It’s a big atom and it will hang around for a couple of weeks.”

Handling How-To’s

If you do need to handle a radioactive mineral specimen, don’t dally. “If you’re working with it for too long, that’s all additional exposure,” Rowan says. “So, the amount of time that you’re in contact with the rock, you need to minimize it. And you need to make sure that you don’t spread contamination everywhere.”

To that end, she suggests wearing protective clothing and disposable gloves and protecting your work surface with a disposable covering. Washing carefully with soap and water is also key. “If you handle a radioactive rock, you’ve got radioactive rock dust on your fingers and you’ve got to wash it off,” Rowan says.

Finally, to prevent ingestion or inhalation of radioactive contaminants, never eat, drink or smoke when working with radioactive minerals, and, Rowan concludes, “Don’t be paranoid, but do take care.”

This story about radioactive minerals appeared in Rock & Gem magazine. Click here to subscribe. Story by Susan M. Brackney.

The post What are Radioactive Minerals? first appeared on Rock & Gem Magazine.

This stone, paradoxically celebrated for its beauty yet feared for its curse, is the Hope Diamond. The size of a walnut and a deep blue gem in color, it is the world’s best-known diamond. Over its 370-year-long, often murky history, it has become immersed in legend, stolen at least twice and cut four times. Its owners have included sultans, kings, bankers, jewelers, thieves, a popular stage performer, and a fabulously wealthy heiress.

Since 1958, the Hope Diamond has been a major attraction at the National Museum of Natural History (Smithsonian Institution) in Washington D.C., where it has been viewed by more than 100 million visitors and is currently valued at over $250 million.

Plucked From the Eye of an Idol

The Hope Diamond’s strange story began in 1653 when French gem merchant Jean-Baptiste Tavernier visited India’s Golconda Sultanate. There he purchased a crudely cut, triangular, flat, blue diamond of extraordinary size—115 carats. According to legend, this diamond, now known as the “Tavernier Diamond,” had been cursed since it previously had been plucked from the eye of a statue of a Hindu idol.

After returning to Europe in 1668, Tavernier sold the diamond to King Louis XIV of France, who ordered the stone recut. Tavernier wrote extensively about the gem before his death in Moscow the following year—when he was reportedly dismembered by a pack of wild dogs.

The “French Blue” and the Guillotine

The 1691 French crown jewel inventory describes the recut stone as “a very big, violet (the period term for “blue”) diamond, thick, cut with facets on both sides and in the shape of a heart with eight main faces.” It weighed 67.1 carats and was valued at the equivalent of $4 million in 2023 dollars. Formally known as the Blue Diamond of the Crown of France and popularly as the “French Blue,” this smaller stone, with its enhanced symmetry and additional pavilion facets, was substantially more brilliant than the original Tavernier Diamond. The French Blue was likely the first large diamond to be cut in a modern brilliant style.

Louis XIV had the blue diamond, along with a 117-carat red spinel and 195 smaller diamonds, set in an elaborate pendant that symbolized the Order of the Golden Fleece, a Catholic order of chivalry. Despite this prestigious setting, the idea that the French Blue was cursed gained credibility with the misfortunes of Louis XIV. Five of his legitimate children died in infancy. And the king himself died in agony of gangrene in 1715.

Setting the Stage

Ownership of the French Blue then passed to Louis XV, a monarch who enjoyed great popularity early in his reign—but his good fortune did not last. He engaged in costly wars that drained the French treasury, weakened royal authority, and set the stage for the French Revolution. Louis XV died a hated man in 1774.

The French Blue then became the property of King Louis XVI and his wife, the infamous Marie Antoinette, both of whom often wore the stone. But when the French Revolution erupted in 1789, the monarchy fell and, in September 1792, Louis was beheaded in a public execution. Marie Antoinette also died at the guillotine four months later.

A Convoluted Trail

During the French Revolution, the blue diamond, now widely believed to be cursed, was stolen from a royal warehouse and never seen again, at least not as the French Blue. The history of the stone then became uncertain. In 1812, just as the statute of limitations regarding the theft took effect, a 45-carat blue diamond appeared in the hands of London diamond merchant Daniel Eliason. Amid widespread accusations that this diamond was actually a cut-down version of the stolen French Blue, Eliason committed suicide.

In 1820, Britain’s King George IV acquired the diamond. Following his death in 1830, his bankrupt estate sold the stone to pay off debts. Attention then shifted to London banking heir Henry Philip Hope, who some suspected had secretly bought the diamond from French thieves in the early 1800s. Hope publicly listed the stone in his 1839 gem catalog—only to die just months later.

The Hope Diamond

The blue diamond remained with the Hope family for the next 57 years, the last owner being the American actress, playwright, and concert-hall singer May Yohé (Mary Augusta Yohé, Lady Francis Hope), whose writings and stage productions often called attention to the stone’s purported curse. The diamond was sold in 1896 to settle Yohé’s pressing debts. Many believed that the celebrated singer herself fell victim to the stone’s evil power: After enduring two disastrous marriages, she died in poverty in 1938.

The blue diamond, now known as the “Hope Diamond,” next passed through the hands of several gem merchants and jewelers, and two Ottoman sultans. The stone was then acquired by the prestigious Paris jewelry firm Cartier and director Pierre Cartier, a renowned wheeler-dealer in the gem world, who immediately began seeking a buyer and a quick profit.

On to America

The story of how the Hope Diamond came to the United States began in 1896 in the gold-mining camp of Ouray, Colorado, where prospector Thomas F. Walsh bought two abandoned claims for back taxes. This purchase turned out to be one of history’s greatest bargains, for the original claim owners had somehow overlooked a massive deposit of phenomenally rich gold ore.

In 1898, Walsh’s daughter Evalyn married Edward “Ned” Beale McLean, heir to The Washington Post newspaper fortune, and became an internationally known socialite with lavish tastes, especially for fine gems. When Thomas Walsh died in 1910, he left his fortune of $3 million ($90 million in 2023 dollars) to his 24-year-old daughter Evalyn Walsh McLean.

Pierre Cartier

Having previously sold fine gems to Evalyn, Pierre Cartier knew that the heiress, now in receipt of her fortune, was a prime candidate to buy the Hope Diamond. Pierre’s first attempt to sell her the stone failed. But he tried again, this time with the diamond set in a striking modern mount surrounded by a three-tiered circlet of dozens of smaller white diamonds.

Also astutely guessing that Evalyn would be fascinated by the stone’s purported curse, Pierre recounted—and likely embellished— its more disturbing details. In 1911, amid great publicity, Evalyn bought the Hope Diamond for $300,000 ($9 million in 2023 dollars). Enamored of the stone, the heiress frequently wore it at balls and parties, at times hanging it around the neck of her Great Dane or hiding it in the furniture and challenging her guests to “find the Hope.”

But in the end, Evalyn also seems to have paid dearly for owning the Hope Diamond: Her husband died in a mental hospital, her firstborn son was fatally struck by an automobile at age nine, and her 24-year-old daughter died of an overdose of sleeping pills.

Harry Winston & The Smithsonian

In 1947, New York City diamond merchant Harry Winston purchased the Hope Diamond from Evalyn Walsh McLean’s estate.

For nearly a decade, Winston displayed the stone on his popular “Court of Jewels” tour across North America, showing it at charity balls and on television shows. He ordered a minor recutting of the stone’s pavilion facets to further increase its brilliance—the fourth and last time that the Hope would be cut.

In the mid-1950s, mineralogist George Switzer, an associate curator at the National Museum of Natural History (Smithsonian), proposed establishing a national gem collection with the Hope Diamond as the centerpiece. Switzer asked Harry Winston to donate the stone to the Smithsonian. In 1958, Winston, intrigued by the idea of a national gem collection and perhaps even more so by a monumental tax write-off, agreed.

Winston sent the Hope Diamond from New York City to the Smithsonian in Washington, D.C., by registered, insured first-class mail. And what happened next convinced many that the Hope’s curse was still alive. Shortly after hand-delivering the stone, United States Post Office letter carrier James Todd was seriously injured in two back-to-back automobile accidents—before losing his house to a fire.

New Look at an Old Stone

For centuries, no conclusive proof existed that the Hope Diamond had been cut from the French Blue, or that the latter had been cut from the Tavernier Diamond. But in 2007, a Paris museum curator discovered a lead cast of the French Blue from which researchers prepared a three-dimensional, digital image. Comparisons with images of the Hope Diamond proved that the Hope had indeed been cut from the French Blue.

Researchers then computer-imaged the Tavernier Diamond based on Jean-Baptiste Tavernier’s detailed drawings from the late 1660s. Image comparisons confirmed that both the Hope Diamond and the French Blue had once been the Tavernier Diamond

A museum cataloging label also indicated that the lead cast of the French Blue dated to 1812 when the stone’s owner was a “Mr. Hoppe of London,” strongly suggesting that Henry Philip Hope had acquired the diamond not long after its theft during the French Revolution, then recut it to disguise its identity to avoid a French repossession lawsuit. After apparently passing the diamond on to Daniel Eliason, Hope seems to have reacquired the stone 25 years later shortly before his death.

“Proof” of the Curse?

Researchers have also learned that the Hope Diamond, when exposed to shortwave ultraviolet light, glows like a burning red ember. While many blue diamonds exhibit this same fluorescence, none match the Hope’s fiery intensity. Gemologists attribute this unusual fluorescence to traces of boron that also produce the Hope’s distinctive blue color. This boron interacts with other trace impurities, enabling electrons within the stone’s crystal lattice to absorb energy from ultraviolet light, and then release it as visible red light.

While gemologists agree that this fluorescence adds to Hope’s uniqueness, intrigue, and mystery, others attribute its eerie red glow to a demonic presence.

Despite the dark legends that still surround the Hope, this celebrated blue diamond has certainly not cursed the Smithsonian, which has benefited enormously through worldwide attention along with substantially increased gifting and visitor attendance.

This story about the Hope Diamond curse previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Steve Voynick.

The post The Hope Diamond Curse first appeared on Rock & Gem Magazine.

Everything is Energy

While this connection might seem puzzling on the surface, it all boils down to energy. Samantha Fey, author, teacher and co-host of the podcast, Psychic Teachers, said, “Crystals have the piezoelectric effect, so they do generate energy. They grow with their own unique vibration and lattice structures.”

This phenomenon occurs when pressure is put on particular crystals, such as quartz, causing the atoms within the stone to move, subsequently turning mechanical energy into electrical energy. This is why crystals are used in watches, televisions and cell phones. It’s this inherent energy that resonates with astrological signs.

Connecting Zodiac Crystals & Sun Signs

Those who are familiar with astrology understand the correlation with the elements — fire, water, air, and earth — and how they offer a glimpse into personality characteristics. When working with crystals according to sun signs, it’s helpful to consider the elements and how they best fit with the particular stones.

Fey used an example of the sun sign Cancer, which is attributed to the moon and is a classic water sign. “They are very watery and ruled by their emotions. Look for crystals with those similar qualities,” she said, such as moonstone.

It’s also important to understand how a stone works with a particular sign in coordination with where we are physically, mentally, and spiritually. “Our energy fluctuates up and down all the time,” Fey said. Depending on what we need, crystals can amplify or balance our actions.

While there are classic combinations of crystals and Zodiac signs, such as obsidian with those under Scorpio, in reality, there are multiple crystals per sign. The choice depends on what you need to do or learn, and this list is a good start to finding a crystal that works for you.

Aries Sign

Notoriously stubborn, Aries people know what they want and are clear about who they are. Fittingly, amazonite is an ideal crystal for this sun sign as it enhances inner strength and the warrior attitude, particularly with women going through significant changes in their lives.

“It’s called the stone of hope and new beginnings,” said Fey, and is excellent for manifesting dreams and goals.

Deb Bowen, co-host on Psychic Teachers, as well as a metaphysical teacher and author, recommends Sardonyx because it is excellent in the realm of self-control and discipline.

“It’s really good for communicating relationships,” she noted because Aries can have sticking points in this area.

Taurus Sign

An earth sign, Taureans, are grounded people who are nurturing and comforting to those most important to them. Being a bull, they are known for their stubbornness and uncompromising nature.

The beautiful light blue to green, or sometimes white kyanite is good for Taureans because it helps clear and align the chakras, according to Bowen. It also builds stability and trust and is excellent for communication. Kyanite cannot hold negative energy.

Fey recommended, ”Carnelian is a great stone for bringing in creativity, positivity and joy. It’s the cheerleader of the stones and it keeps the other stones together.”

Gemini Sign

When a “twin” is around, there’s never a dull moment. Geminis are known to have lots of energy and are very talkative. They can also be indecisive and impulsive.

The green and smooth gem serpentine is a good fit for a Gemini. “It helps you to align your soul’s purpose,” explained Bowen as it enhances the heart chakra. She noted that it also offers protection against the dark arts.

Cancer Sign

Cancer is the classic mother of the Zodiac who is family-oriented, intuitive, and a tad moody. Not surprisingly, the “crab” is their sign.

Bowen said, “Sometimes cancer folks can get sad or depressed.” Because of this tendency, she said blue chalcedony is a good choice. “It helps cancer to communicate the truth. It also dispels negative energies and activates positive changes. It’s a great stone for those who seek general positive shifts in their lives.”

Leo Sign

Leo is known to love being the center of attention with their bigger-than-life energy. They’re also loyal, generous, and loving. The funny thing is, their negative traits simply seem to be their positive traits on overdrive.

Because of this desire to shine, citrine is the stone for Leos. ”Citrine is like your own personal sun,” said Fey. This yellow-to-orange type of quartz appears charged by the sun. Unfortunately, natural citrine is a rare stone and much of what we find is heat-treated amethyst (enhanced gemstones). It’s also well-known to manifest abundance, a natural quality of Leos, and is sometimes called the “stone of success” or the “merchant’s stone.”

Virgo Sign

Logical and energetic, Virgos thrive with well-organized and practical goals, while on the flip side, they tend to overthink situations and can often seem aloof and detached.

Resembling the blues and greens of the earth, the mineral chrysocolla is often found in copper deposits and referred to as the “Stone of the Goddess,” with famous figures, such as Cleopatra, valuing its beauty and energy.

Fey said chrysocolla is like a happy-go-lucky friend. “It’s a great stone for everything. It helps people face some hard truths,” she said. She also recommended that those working with this stone visualize their goals going into the stone.

Libra Sign

The scales represent Libra’s desire for fairness and balance, which is the center of this witty, smart and outgoing soul. With Venus as their ruling planet, they are all about love but will carry a grudge if slighted.

“Libras look at both sides differently, or rather it’s difficult to choose sides,” said Bowen, who is a Libra. She said bloodstone is good because it balances everything, including Libra’s energy. “It helps level folks be present in the here and now.”

Scorpio Sign

Scorpios get a bad rap as being secretive, defensive and vindictive, but their emotions run deep (even if they don’t show it), and they are passionate about whatever, and whoever, they love.

“Malachite is the drill sergeant,” said Fey. “It’s the only stone that breaks to warn you when something wicked this way comes. It’s great for protection.” This rich green stone is also an important part of facing Scorpio’s shadow side. Fey said, “It’s like a friend that is in your face.”

Known as the stone of transition, Bowen said, “Charoite connects the heart and crown chakras.” It allows someone to focus on self-love when setting healthy boundaries.

Sagittarius Sign

Ruled by Jupiter, Sagittarius people are gregarious and big dreamers but can be blunt and preachy.

Fey recommends labradorite that resembles the aurora borealis with its color-shifting nature where one moment it looks gray, the next is shimmering blues and greens. “It helps block the emotions and stuff around you that’s not yours. It’s more like a filter. It lets the good stuff come in and the bad stuff goes out,” she said.

Capricorn Sign

With Saturn as the taskmaster, Capricorns get things done. Although they are disciplined and responsible, this can shift into a level of condescension toward others.

Amethyst is the go-to for these hardworking signs. “It cleans, clears, and heals everything around it,” said Bowen. ”It’s a balancing, protective and loving stone. It’s a great stone to connect. It fights off temptation and works with decision-making. It’s good for sleeping and it protects them from nightmares.”

Once used by the Romans to fend off the evil eye, tiger’s eye is protective and balancing. Fey said, “It works with your energy to establish a foundation and recognize patterns of things that no longer serve you. She said to place tiger’s eye on the solar plexus during meditation for courage and confidence, as well as to shift toxic energy into positive ones.

Aquarius Sign

Quirky and unconventional, the highly social Aquarians champion humanitarian efforts and relish deep conversations. Yet, they are not known for being the most emotionally open individuals and might appear aloof.

“Aquarians are ahead of their time,” said Fey. “Dark, ruby red garnets help them recharge and revitalize their energy. Write down goals and dreams for the year and place garnets on top of the list.”

The ornamental chrysanthemum stone is typically all black except for a splash of white in the middle resembling a flower. Bowen recommended it for Aquarians because ”it brings to us child-like energy and being able to live in the moment.”

Pisces Sign

The astrological fish who swim in deep waters are philosophical, intuitive and creative, yet at times, spend too much time in their own heads.

To counteract this latter tendency, aquamarine, which is often called the “stone of courage” boosts confidence for the Pisces people. Bowen said, “It’s such a beautiful stone. It helps one to always be prepared.” Legend says aquamarine was spilled from a mermaid’s treasure chest and it was supposedly blessed by Neptune.

Fey recommended fluorite to clear negative energy. Called the student’s stone, she said, “It’s created for cleansing the aura. It eliminates negative patterns and helps you to see your path more clearly,” said Fey. She also mentioned it is effective in blocking electromagnetic fields and is often kept near the computer to minimize exposure.

Picking the right stone for you is a matter of listening to the universe. “It’s really important when you buy sun sign crystals that the stone speaks deep, deep into your soul,” said Bowen.

“It’s great to read and study, but at the end of the day, you have to go with the crystal that resonates with you,” noted Fey. “Walk into a store that sells stones and see what you’re drawn to. Find your buddy and stick with it for a while.”

*The metaphysical properties discussed in this article are not intended as a substitute for traditional medical treatment. If you have a health issue, please seek a licensed medical professional. The crystals and stones discussed are not intended to diagnose, treat or cure any conditions.

This story about zodiac crystals previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Amy Grisak.

The post Best Crystals for Your Zodiac Sign first appeared on Rock & Gem Magazine.

Black diamond refers to both carbonado diamonds and black gem diamonds, they are not a diamond alternative and they are not synthetic diamonds. Carbonado, a rare type of diamond with a polycrystalline structure, is not normally considered a gemstone. Nevertheless, super large diamonds like large, faceted carbonados sell for several million dollars. Black gem diamonds, on the other hand, are a color variety of monocrystalline, or “single-crystal,” diamonds—the familiar stones we see in jewelry stores.

Carbonado Black Diamonds

In 1843, Brazilian placer miners discovered dense, opaque, black pebbles and cobbles that they named “carbonado,” after the Portuguese carbonizado, meaning “carbonized” or “burned” and alluding to their charred appearance. Mineralogists subsequently described carbonado as a previously unknown form of diamond with a polycrystalline structure and consisting of tightly bonded aggregates of randomly arranged diamond microcrystals.

Carbonado had no value until the 1870 introduction of diamond-studded drill bits. With its greater hardness and durability, along with a microcrystalline structure that provided more cutting edges, carbonado’s rock-cutting ability far exceeded that of a monocrystalline diamond.

Industrial demand for carbonado soared and, by 1880, Brazil was mining 70,000 carats (30.9 pounds) per year and selling it to the United States and Europe for $20 per carat. Carbonado-studded drill bits were later used extensively in building the Panama Canal and developing Minnesota’s great open-pit iron mines. Carbonado has now been replaced by synthetic polycrystalline diamond and is no longer mined commercially

The Great Carbonados

Carbonado diamonds are quite rare. Only an estimated three tons have been mined in the past 150 years—almost nothing compared with the 25 tons of monocrystalline diamonds now mined worldwide each year. Despite its scarcity, carbonado has provided many extraordinary specimens.

In 1895, Brazilian placer miner Sérgio Borges de Carvalho recovered a huge carbonado of 3,167 carats (22.34 ounces). Weighing 61 carats more than South Africa’s fabled Cullinan Diamond (monocrystalline), it was the largest diamond of any kind ever found. The “Sérgio Diamond,” named in de Carvalho’s honor, sold for $16,000 ($500,000 in 2023 dollars). Unfortunately, it was broken up into cutting studs for drill bits.

Of the few gems ever cut from Carbonado, the most spectacular is the Enigma Diamond. The world’s largest faceted diamond, the Enigma sold in 2022 in a highly publicized auction for $4.3 million. The preponderance of “fives” in this irregularly cut, 55-facet, 555.55-carat gem is not coincidental: Its previous owner, an Arab tycoon, styled its cut after the ancient Mideastern hamsa amulet, which both Jewish and Arabic traditions associate with the number five.

The Origin of Carbonado

Scientists initially assumed that both polycrystalline and monocrystalline diamonds formed in the extreme heat and pressure of the Earth’s mantle and were later emplaced in surface kimberlite pipes. But carbonado does not occur in association with monocrystalline diamonds.

By the 1970s, researchers had concluded that carbonado’s unusual inclusions indicated not mantle formation, but rather meteoric origin. They also noted that because carbonado in quantity was found only in Bahia, Brazil, and the Ubangi River region of the Central African Republic—and in the same geologic horizons—it had likely fallen to Earth in a single, massive meteoric event when South America and Africa were joined as one landmass.

Many scientists now believe that carbonado formed on exploding red giants (large stars with low surface temperatures) when shock waves compressed carbon into polycrystalline diamonds before hurling it into space where some eventually reached Earth as meteorites.

Black Diamonds

Meanwhile, as scientists continued to debate the origin of carbonado, black monocrystalline diamonds were gaining popularity as faceted gems. Their black color and opacity are caused by numerous tiny inclusions, most often of graphite or amorphous carbon.

Only about 1 in 10,000 monocrystalline diamonds is naturally black. Historically, these stones had no gem value until the 1990s when they began appearing in white gold and platinum settings accompanied by colorless melee diamonds. These black monocrystalline diamonds also began attracting metaphysical interest as stones that provide wearers with power, determination, and inner strength.

Natural vs. Treated

Faceted, natural, black monocrystalline diamonds now sell for about $2,500 per carat. But most black-diamond gems currently being sold started as heavily included, grayish, industrial-grade diamonds. Heating these low-value stones to 1300°C for several hours converts tiny inclusions of amorphous carbon to graphite which absorbs white light and produces nearly opaque, very dark green stones that appear black. Today, loose, heat-treated, faceted black diamonds sell for roughly $300 per carat.

The most celebrated natural, black, monocrystalline diamond gem is the 67.5-carat Black Orlov Diamond. Mined as a 195-carat rough crystal, it was believed to be cursed after three of its owners committed suicide. To break the curse, the gem was cut into three pieces, the largest being the Black Orlov. Mounted in a brooch and surrounded by a circle of 108 small, colorless diamonds, the Black Orlov has been displayed at major museums around the world.

So, whether as polycrystalline carbonado or monocrystalline gems, black diamonds are finally gaining the respect they deserve.

This story about black diamonds previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Steve Voynick.

The post Black Diamonds Gain Respect first appeared on Rock & Gem Magazine.

A Form of Coal

Coal is technically a rock, a combustible material formed by the decomposition and destructive distillation of biomass material in an oxygen-free environment. Coalification, the process of coal formation, begins when layers of plant material become buried and compressed under new forest growth and sediments. Elevated temperatures and pressures then alter these organic remains, driving off water and volatile compounds and concentrating the carbon in the remaining material.

Coal consists primarily of carbon, together with some oxygen and hydrogen, and smaller amounts of sulfur, iron, nitrogen and other elements. Variations in burial time, heat and pressure produce four basic commercial grades of coal: peat, lignite, bituminous (including subbituminous) and anthracite. Peat, a brown, crumbly precursor to true coal, contains only about 25 percent carbon.

But with longer burial times and increased heat and pressure, peat will alter into lignite, which consists of 30 to 40 percent carbon. Subbituminous and bituminous coal, called “soft coal,” contains 40 to 90 percent carbon and has a hardness of Mohs 2.0-2.5. Anthracite or “hard coal” consists of more than 90 percent carbon; at Mohs 2.5-3.0, anthracite is the hardest type of commercial coal.

The Origin of Jet

Jet is technically a rare type of lignite. While all commercial coals are derived from massive accumulations of plant matter and occur in seams ranging in thickness from a few feet to several hundred feet, jet is formed from individual tree trunks that became waterlogged, sank, and was buried in organic-rich sediments. Jet does not occur in massive seams, only in small, isolated pockets rarely more than a few inches in thickness.

Also unlike other types of coal, the structural and chemical nature of jet is influenced by the geochemical environment of the surrounding host rock, which is usually an organic-rich shale. As the jet develops, it absorbs oils and other hydrocarbon materials that are released by the decay of algae, plankton, and similar types of organic matter within the shale. Subsequently, the jet exhibits neither the extreme brittleness nor the extensive fracture systems common to other forms of coal.

At Mohs 3.0 to 4.0, the jet is by far the hardest type of coal. It is classified either as “hard jet,” which forms in marine environments, or “soft jet,” which develops in lacustrine or freshwater environments. All jet is opaque and exhibits a uniform, fine grain and a waxy-to velvety luster. It is easily carved and polishes to an attractive matte finish or a high sheen.

Jet consists of roughly 75 percent carbon, 12 percent oxygen, and lesser amounts of sulfur and hydrogen. It is easy to identify: when touched with a red-hot needle, jet emits a distinctive, coal-like odor.

A Jet History

Jet was collected and carved in Neolithic times. The oldest known jet artifact, recovered from a gravesite in Germany, dates to about 9000 B.C., making jet one of the oldest worked gem materials.

Whitby, located in Yorkshire in northeast England on the coast of the North Sea, has always been the world’s premier source of high-quality jet. The systematic collecting of jet for trading purposes had begun on the Whitby beaches by 1500 B.C. Jet later became especially popular among the Romans who obtained it from the same beaches.

Whitby jet, which is nearly altered to a subbituminous state, originated about 180 million years ago in a Jurassic Period saltwater swamp. The jet that washes onto the Whitby beaches is periodically replenished when North Sea storms erode the sea bottom. Some pieces of Whitby jet retain the shape of the original tree branches and trunks and are especially valuable as collector specimens.

By the time the popularity of jet jewelry peaked in England during the 1870s, collecting and working jet had become an industry in Whitby and a major part of the local economy. More than 1,000 Whitby residents were involved in collecting, working, or marketing jet, which was fashioned into cabochons and beads for jewelry, and into an array of small decorative objects, all of which were traded throughout the British Isles, Europe, and North America.

Jet the Gemstone

Part of jet’s popularity as a gem is because of its very low density. With a specific gravity of only 1.3-1.4, jet is half as dense as other black gemstones—a big advantage when wearing the long, bulky necklaces popular in Victorian Era mourning jewelry and the multiple-strand, “flapper” necklaces of the Roaring Twenties. Jet is also one of the few opaque gem materials that is commonly faceted.

Jet’s popularity in jewelry began fading during the 1930s in the face of competition from schorl (black tourmaline); dyed chalcedony; inexpensive imitations including black glass, plastic, and vulcanized rubber; and the growing acceptance of Art Deco jewelry styles which made little use of black gem materials.

Although Whitby remains the leading source of jet, this gem variety of coal is also found in Spain, France, Germany, Poland, Turkey, and Canada. In the United States, jet is found in Colorado and Utah where certain Native American groups continue to use it in jewelry and ceremonial objects, often in combination with turquoise and red coral.

Available today as beads, cabochons, and small decorative objects, as well as natural specimens, jet retains its distinctive identity as the rarest type of coal, one of the few organic gemstones and, thanks to William Shakespeare, an enduring simile for the color black.

This story about jet stone previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Steve Voynick.

The post Jet Stone 101 first appeared on Rock & Gem Magazine.

January

Garnet has been the birthstone for January since the 15th century, at least. With a Mohs hardness of 6.5 to 7.5, it can be faceted into beautiful gemstones that wear well in jewelry. Since the term “garnet” actually refers to a group of nesosilicate gems, those born in this month can choose from a rainbow of colors.

The most common members are red almandine, an iron-aluminum silicate; red pyrope, a magnesium aluminum silicate; orange-yellow spessartine, a manganese aluminum silicate; the yellow or green varieties of andradite, a calcium-iron silicate; predominately green grossular, a calcium-aluminum silicate; and rare, bright-green uvarovite, a calcium chromium silicate.

February

From the 15th century to the present, amethyst has been the preferred birthstone for February. Amethyst belongs to a mineral family that can compete with garnet for diversity of color: quartz.

Pure quartz is colorless, as exemplified by Herkimer diamonds. The causes of amethyst’s shades of pale violet to rich purple are radiation and the inclusion of iron impurities and trace elements.

As a rule, amethyst crystals are short and stubby, and occur in large numbers, often filling a large vug a hollow petrified tree section, or lining the inside of a geode. Fine crystals that are large enough to produce a faceted gem of over 20 carats are rare.

March

The current choice of a birthstone for March is aquamarine. Aquamarine is a variety of beryl (Mohs 7.5-8). Its name was derived from the fact that the beautiful, transparent, blue-green coloration of the gem resembles that of seawater. It can be found in translucent to transparent crystals that form in the hexagonal system. The six-sided crystals are often striated lengthwise.

Aquamarine develops in metamorphic rocks and, more often, in pegmatites.

April

Before 1900, a person with an April birthday had two choices of birthstone: diamond or sapphire. During the 20th century, however, diamonds became the preferred stone.

Diamond, a mineral consisting of pure carbon, heads the list of all gemstones for its beauty and hardness. A 10 on the Mohs Scale of Hardness, it is resistant to scratching and is an ideal gem to set in rings. Its hardness results from the arrangement of its atoms in cubes.

All diamonds have slightly rounded faces, and they’re so smooth they feel greasy to the touch. They can be colorless and water clear to blue, pink, yellow, brown, green or black, and transparent or translucent. They shine with an adamantine luster when held to the light.

May

There were two choices for May birthstones for several hundred years: emerald and agate. The popularity of agate seems to have waned at the turn of the 20th century, so emerald is now the favorite. It’s the green member of the beryl family of gemstones. The color varies from bright green to pale green and, sometimes, darker shades of blue-green.

Fine emeralds have a velvety surface appearance and, in the better stones, an even distribution of color. One bad trait of emeralds is a tendency to have inclusions. It’s rare to find an emerald without some slight imperfection. This in no way deters from the beauty of this gemstone, though. It can also be one way of determining whether an emerald is a simulated gem or the real thing, as manmade stones have no imperfections.

June

The contemporary choices for June are pearl, moonstone and alexandrite. Of course, a pearl is the organic product of marine bivalves and not a mineral.

Moonstone is a variety of feldspar that shows adularescence, or schiller, an optical effect that produces a milky luster with a bluish tinge that appears to move across the stone when it is tilted. The phenomenon is named after the feldspar variety adularia.

Alexandrite is a color-change variety of chrysoberyl (beryllium aluminum oxide). This is a very rare and expensive gemstone. It has a hardness of 8.5, and its crystals are either tabular or prismatic. The distinction between alexandrite and chrysoberyl is simply color. A strange characteristic of alexandrite is that it is red, purple or violet when held under artificial light, but in daylight, it looks green.

July

Ruby is the standard birthstone for the month of July. It is a corundum (aluminum oxide) gem that gets its color from the presence of chromium in its structure. An exceptionally hard mineral, corundum illustrates a hardness of nine on the Mohs scale. “Pigeon-blood” red is the preferred color for rubies, though they also occur in lighter shades, including pink. All other colors of corundum are called sapphires.

Ruby exhibits all the desirable properties of a jewelry stone: beauty, durability, optical properties, and rarity. Some rubies display a star or asterism when fashioned into a cabochon. This effect is caused by the reflection of light from numerous inclusions of minute, needle-like crystals of rutile. Corundum crystallizes in the hexagonal system with a tabular-barrel-shaped habit.

August

Current birthstones for August are peridot, the gem-quality form of olivine and spinel. Olivine makes up a large portion of the earth’s mantle. Rocks containing olivine have been brought to the surface by volcanic action and actually blown out in the form of volcanic bombs. Masses of olivine have been found in meteorites, and the Apollo astronauts brought basaltic rocks back from the moon that contained olivine.

A popular jewelry stone, peridot has a hardness of 6.5-7 and can be transparent or translucent, with a vitreous luster. Its color shades from deep green to apple green, yellow-green or olive. It’s most often found in granular nodules, forming short, prismatic crystals in the orthorhombic system.

Spinel is the gem-quality member of the larger spinel group. Its hardness (Mohs 7.5-8.0) makes it ideal for jewelry use. Its spectrum of colors includes red, pink, purple, blue and lavender. In times past, red spinel was often mistaken for ruby. A notable example is the Black Prince’s Ruby, set in the royal crown of England.

September

The birthstone for September is sapphire. This term refers to any corundum (aluminum oxide) gem that has any color other than red (ruby). Sapphires may be colorless, blue, green, yellow, orange, brown, pink, purple, gray, black, or multicolor. At Mohs 9, its hardness is second only to that of a diamond.

Heat treatment is sometimes used to give natural blue sapphires a deeper, more pleasing color. Natural star sapphires, which display the optical phenomenon of asterism, are very rare.

October

Two options for October are opal and tourmaline. Opal is a magnificent gemstone with a play of color or “fire” in all colors of the spectrum. Spaces between the tiny spherules of silica that make up the gem diffract light into its spectral colors. Red, yellow, green and blue, in strong to pastel shades, flash from the stone when it is tilted.

Opal occurs in common and precious types. Common opal does not display any reflective fire. It may have a honey-yellow, brown, gray or colorless body color that is milky and opaque. Opal (Mohs 5-6) is not a very hard gemstone.

Tourmaline, a silicate of boron, has a complicated chemical composition, in which a number of elements, including calcium, iron, sodium and aluminum, may combine. It has a Mohs hardness of 7-7.5.

It belongs to the trigonal crystal system and its habit is hemimorphic (a crystal having two ends of an axes unlike in its planes).

Because of the coloration of the individual stones, tourmaline has several names, including schorl (black), rubellite (red), indicolite (blue), and dravite (brown). Tricolor crystals are common. The popular watermelon variety has an outer layer of green around a red core.

November

The current birthstones for November are topaz and citrine. People tend to think of topaz, a silicate mineral with aluminum and fluorine, as a yellow stone, but heat-treating and color-enhancing adaptations have made blue the predominant color on the market. It is an allochromatic mineral, which means its color is caused by internal defects in the crystal and has a Mohs hardness of eight.

Citrine is the golden member of the quartz family (silicon dioxide). Though quartz in its many forms is one of the most abundant minerals on earth, fine, gem-grade crystals are not that common. Citrine is affordable and, when faceted, rivals more expensive gemstones in beauty.

December

There are three birthstones for December: turquoise, blue zircon and tanzanite. Turquoise (hydrated copper aluminum phosphate) is an opaque, blue-to-green, massive gem material. It has a relatively low hardness of Mohs 5-6, so care must be taken with turquoise jewelry.

The rarest and most valuable variety is robin’s-egg blue with black “spiderweb” veins of limonite. Fake turquoise, consisting of dyed howlite or magnesite, is common. Buyer beware.

Zircon (zirconium silicate) can be blue, black, red, brown, green, yellow, smoky, or water-clear. It has an adamantine luster much like that of a diamond, and it is often misidentified as such.

Tanzanite, the blue/purple variety of zoisite (basic calcium aluminum silicate), is a recently introduced alternative for December. Tanzanite crystals in shades of yellow to brown, green, pink, gray or blue are often heat-treated to produce a gemstone that is a beautiful and permanent blue.

This story about what are birthstones by month previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Kenneth H. Rohn.

The post What are the Birthstones by Month? first appeared on Rock & Gem Magazine.