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.

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.

Whether teaming together for all-female outings, or introducing the world of rocks and minerals to the next generation, women bring a new perspective, and sometimes a different approach, to this age-old endeavor.

Following Her Calling

For some rockhounding women, their affinity for interesting finds started at an early age.

“Ever since I’ve been little, I spent time at Crystal Park, (a recreational area in southwestern Montana where natural crystals abound),” said Brianne Scott, founder of the informal group, Rockhounding Women Montana.

Even though rocks were in her DNA from an early age, Scott went another route, instead earning a degree in Elementary Education, but it wasn’t the right fit. “It’s tough to be in the classroom all day long,” she said. So she stepped away from the profession and started collecting more rocks, mostly for the fun of it.

During her excursions around her Butte home, she said, “ There’s one piece that I have that’s a really neat little piece.” She said she spotted it caked in dirt, but discovered it was a combination of feldspar, smoky quartz castle-like structures, and albite, all coated with epidote. “It’s my favorite because of the complexity of it. It’s so unique.”

“I found myself with an overabundance of rocks,” she said, “ That’s how I got introduced to the rockhounding groups in Montana.”

Finding Other Rockhounding Women

Scott also discovered other groups on social media. Being able to trade or buy specimens not found in her area is one benefit of these connections, along with the opportunity to learn from others’ experiences.

“The biggest thing I’ve noticed about rock people is they are so friendly. I really get that sense of community,” Scott noted. “That’s where the lady rockhounding group started. I’ve gone digging with a lot of boys, but wanted to find more women.”

“We did one field trip in the summer. A group of us gals went to Crystal Park and went digging for the day,” she said. Scott is already lining up field trips, as well as learning opportunities for any of the women who want to participate. “It’s knowing what to look for on your hikes.”

Scott loves hanging out with any rock enthusiast, but women’s groups are sometimes less intimidating to new rockhounds. “I noticed a lot of the men are very technical with things,” Scott explained, which isn’t always conducive to a newbie. She believes women have a broader view of the landscape and notice what’s going on around, or in, the ground.

“Really it’s still a good partnership with men and women. It’s just a different dynamic,” she said.

When it comes to women, or really anyone, who wants to step into this fascinating world, Scott’s best advice is, “Reach out to folks. You’ll be able to find someone who is more than willing.”

Teaching the New Generation

While some rockhounding women are born with rocks in their pockets, others grow into it. Becky Weldy, a high school science teacher in Covington, Ohio, said her interest began during her post-graduate work. At that time, Wright State University offered a Master’s Degree program to educate teachers in geology.

“The professor opened my eyes to it,” Weldy said, particularly because the courses were far from mere academic musing with field trips in the Ozarks, Finger Lakes of New York, as well as the east coast of New Jersey.

Now she offers college-level courses in a high school class, enlightening the students to see beyond the textbooks. “I think a lot of the kids don’t seem to travel as much,” noted Weldy who aims to inspire them and bring the outdoors inside through her curriculum.

Field Trips & School

Weldy plans several field trips throughout the academic year, including visiting the Ohio Caverns, which are geological wonders in and of themselves, as well as Caesars Creek State Park in Waynesville. She said the area was developed by the Army Corps of Engineers in 1938 as flood control. The dam formed Caesar Creek Lake, which at 115 feet deep is the deepest in Ohio, and the spillway is rich in fossils such as trilobites and horn corals. This whole area is known throughout the world as a hotspot for geologists. A permit is required, but she turns the day into a multi-course study for her students.

Weldy also strives to bring her geology studies to the school. ”My other big project is behind our football field in eight acres of woods,” she said. Several years ago, teachers began working to turn the area into a working land lab cutting through new trails, spraying out the invasive honeysuckle, and replanting native trees.

Of course, the elementary kids already love exploring the space, plus Weldy incorporates the natural area into her geology classes with her 11th and 12th graders where they’re able to conduct real-world tests.

“It brings it into perspective to see and to touch,” she said. ”It is eye-opening to a lot of them.”

She hopes that even though she didn’t experience the wonders of geology until later in life, her students will have a jump on an appreciation of the rocks and minerals.

Rocks in Her Pockets

Dr. Kerry Griffis-Kyle, Ph.D., is an associate professor teaching classes involving complex ecosystems at Texas Tech University. Throughout her career, Griffis-Kyle primarily focuses on living things, but rocks are what make her happy.

She laughed when remembering her move from Syracuse to the Southwest when the movers picked up a particularly heavy box and wondered what could be in it. It read: “Rocks and Dead Things.”

Griffis-Kyle said, “That’s what it was because I am a biologist!”

The landscape at her home in Lubbock, Texas, is extraordinarily flat so for years she brought home larger specimens to add visual interest. Now that she is delving into the art of rock tumbling, she has shifted her focus.

“With the rock tumbling I’m picking up smaller rocks,” Griffis-Kyle noted. This focus on tumbling also requires a different form of attention. She’s learned to use a flashlight and black light to inspect the stones for structures within them. But she added, “I need to be better at identifying them. Some rocks are toxic. Some have mercury or uranium in them.” She pointed out that rocks with bright yellows and greens are particularly important to identify and handle properly.

Social Media Connections

In this new endeavor, she said that social media connections, especially with rockhounding women, are invaluable, whether it’s choosing the best rocks or specifics on using the tumbler. It’s a combination of art and science where a strong streak of experience goes a long way.

“I’m paying attention more to where the resources are,” Griffis-Kyle noted. When choosing where to camp, rockhounding is at the top of the activity list, and she enjoys visiting New Mexico. She said the state does an excellent job explaining where you can find different rocks and where it’s permissible to keep them.

She pointed out, “State by state you have to pay attention to what is allowed. Most of the time it’s okay to pick up a few rocks for personal use on federal land, but you can’t pick up fossils and artifacts. And never pick up anything on Park Service or DOD (Department of Defense) land.”

Always a scientist at heart, Griffis-Kyle appreciates the geological processes it requires to create colorful and unique specimens, but in the end, she said she looks for rocks because they make her happy. ”It’s kind of like art appreciation. Different things speak to different people.”

Gaining Knowledge in Groups

Although Valerie Steichen brought home rocks throughout her life, it wasn’t until she attended a rock and gem show in Missoula, Montana, that she noticed the long list of field trips hosted by the Hellgate Mineral Society. She was immediately on board.

“ They’re looking for young members,” said Steichen, noting the reality is many people within the group are over 70 years old, a common trend of these types of groups. There are lifetimes of knowledge waiting to be shared with the next generations, which is one of the main reasons Steichen appreciates the group.

“The main reason I go is so I get to walk in the forest with a geologist and learn,” she said. And besides the fieldwork, the club offers numerous educational workshops to keep everyone sharp.

Joining the Men

Whether it’s potentially the older membership and generational differences or an intimidation factor for women who are new to rockhounding, Steichen noted that when they go on field trips, the group is roughly 90 percent men.

But she is quick to allay concerns and encourages rockhounding women, and younger people in general, to join a local mineral or gem hunting group. “All of them are friendly,” she said.

Besides the innate knowledge of the landscape and the minerals found within it, Steichen noted, “What really struck me is their responsibility for nature.” She appreciates the knowledge of how to ethically dig for minerals, which is a growing concern in some regions when, at times, visitors take too much or do not practice Leave No Trace principles. By digging with one of these well-educated groups, new enthusiasts learn how to protect the resources for everyone.

For Steichen, one of her favorite finds is agates, which is the state rock for Montana. “I think I can pick out agate at a mile away. They look like ugly rocks, but they have billions of years of a story to tell,” she said.

And while the finds are beautiful, there are stories behind each one. Steichen said, “I remember where I found the rocks. There are memories to it and it means something.” So whether she is rock hunting with the Mineral Society members or looking for agates with her family, Steichen is the mineral matriarch who passes on this knowledge to anyone who wants to learn.

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

The post Rockhounding Women first appeared on Rock & Gem Magazine.

Purchasing Ghost Fire Agate

Since this is a new material, it’s not readily available everywhere just yet, it can be found mostly on Facebook in some of the rock sales forums. When buying ghost fire agate, it’s best to buy from pictures that show at least one side faced, or cut in half, so that you can see what you are getting inside. This material has a great deal of matrix on the outside, and a greater portion inside. It’s best to see how much agate is there before committing to a price that might not yield enough usable agate area to cab since it’s purchased by the pound.

Slabbing Ghost Fire Agate

When starting to slab this material, I cut from two sides, north and west. This way I could see if there were drusy pockets or completely agate-filled nodules. I was able to choose which patterns I liked best. There is no definitive direction to load the stone in the vice, as there are no north-to-south types of patterns in this stone. Start off with the flat sides held tight in the vice. Once you get it cut, if there are large areas of the matrix in the center, I like to cut through them, and downsize the larger stones, so that I can cut smaller ones on a 10-inch trim saw. That way it’s much easier to switch directions with each slab cut, instead of continually loading a vice on the larger saws.

Once your slabs are cut, and it’s time to draw preform designs, you can include some of the matrix that’s still solid enough to cab and not worry about undercutting too much. I have noticed that the plumes grow from areas of the matrix, so I designed them in a way that the matrix is used as a partial framing of the cab. Other times, you can run into patches of beautiful purple and blue agate and isolate that as your cab. The other pitfall to look out for is the calcite that seems to border some of these areas. It’s much softer than the agate and will undercut fairly easily, especially if it’s on the edge of your cab.

Cabbing & Finishing

The cabbing process is fairly routine to most agates, but there are still several ways you can go to obtain the same results. Most lapidaries use a 6-diamond grit wheel setup. For those who still have, or use silicon carbide belts on a poly arbor, they seem to work well in the beginning stages as long as they are on two separate machines, and you rinse the cab off before going back to diamond grit, to keep from contaminating the machine with diamond wheels.

Start shaping and doming on the 80-grit steel diamond wheel. Once you have that portion done, you can continue to a 140 soft resin diamond wheel, or switch to a poly arbor set up, with 100 and 220 silicon carbide belts. The 100 will quickly smooth out the cab and remove all the deep scratches from the 80-grit. The 220 will completely remove any remaining scratches, making it quick and easy to finish the rest of the way on the diamond wheels, starting back on the 600, and all the way up to the 14k.

This story about ghost fire agate previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Russ Kaniuth.

The post Ghost Fire Agate: What to Cut first appeared on Rock & Gem Magazine.

This iconic World Heritage Site encapsulates a central theme of “Paradise” with its harmonious blending of so many elements including the phrase “Enter Thou My Paradise” inscribed over one entrance.

The Taj Mahal, which translates as the “Crown of Palaces,” has been called the jewel of Muslim art in India. This “ultimate symbol of love and loss” perched above the Yamuna River in Agra in the state of Uttar Pradesh, began with Mughal emperor Shah Jahan, who reigned from 1628 to 1658.

Keeping a Memory Alive

Although he had many wives, Jahan had one great love, his wife Mumtaz Mahal, who died while giving birth to their fourteenth child in 1631. It is said Jahan’s hair turned gray overnight in his grief. To keep his wife’s memory alive forever, he immediately commissioned a great mausoleum to house her remains. Eventually, it would also serve as the tomb of Jahan himself, forever side-by-side with Mumtaz in what was meant to replicate paradise on earth.

Construction began in 1632, and the famous white marble mausoleum was completed in 1648. It took another five years (until 1653) to complete the entire 42-acre complex, which includes reflecting pools, courtyards, gardens, cloisters, crenelated walls, and associated majestic buildings (including a mosque and a guesthouse) constructed in red sandstone from Delhi. But the 115-foot high dome of the mausoleum stands out as the centerpiece. Its translucent white marble from Makrana quarries in Rajasthan (transported nearly 500 miles via bullock carts and elephants) contrasts with the red sandstone of the surrounding buildings and walls. The color of the marble shifts with the hours of the day : pink in the rising sun, white in strong daylight, golden-hued at sunset and under the moon. Some say this was intentional, to replicate the ever-shifting moods of Mumtaz.

Surprising Materials

A surprise for many is that the Taj Mahal is more brickwork than marble. The white marble forms just a thin veneer. Had it been crafted entirely of marble blocks, the tomb would not have been able to support its own weight.

Under the supervision of Ustad Ahmad Lahauri and a board of court architects, construction involved masons, stonecutters, sculptors, and inlay artisans along with the best calligraphers in the land. In all, more than 20,000 laborers formed a city-within-city surrounding the complex in a project that, in its day, was comparable to the Apollo moon shot of the 1960s. And its cost was similarly exorbitant.

How much would it cost to build the Taj Mahal today? Sources are conflicting. In U.S. dollars, numbers range from as low as $70 million to as high as $1 billion. No matter how you do the math and the exchange rate, that is a lot of rupees!

Symbolic Designs

Because the Islamic faith forbids the use of human faces or imagery in decoration, the surface of the mausoleum relies on symbolism to reflect both natural beauty and divinity. Per one source, it was designed to represent “an earthly replica of one of the houses of Paradise.”

Floral Symbols

Architects chose abstract geometric forms, including herringbone inlays here and there, but especially floral designs. Flowers were considered natural symbols of the divine realm.

The designs include realistic vases, flowers, and vines carved in three-dimensional relief and polished within the marble on some panels. Such carved relief works particularly grace the lower portions of the walls.

What really catches the eye are the inlays of stylized flowers. While commonly called peitra dura (“hard stone”) from Italian traditions, in India it is called parchin kari. Precious and semi-precious stones ranging from large slabs to tiny slivers were cut, shaped, polished, inlaid, and leveled to the enclosing marble. The floral patterns they represent include tulips, lilies, irises, poppies, and narcissus. To create shaded effects, a single flower might have a dozen or more carnelian pieces in colors of varied intensity.

Taj Mahal Pattern Books

To this day, Indian artisans hold “pattern books” to craft designs originating with the Taj Mahal into marble countertops, tables, and small jewelry boxes. While few of us will ever be in a position to create or purchase a monument on the scale of the Taj Mahal, parchin kari has long been a vibrant cottage industry in this region of India.

But buyer beware! Quality varies considerably, from the finest marble that is highly durable and takes a fine polish to soft, porous marble or even soapstone that may be inlaid with plastics. The real deal is stunning to behold.

While parchin kari in airport gift shops may go for cheap, Shah Jahan spared no expense in sourcing stones for inlay from all around India, the Middle East, and Asia to grace the mausoleum for his beloved Mumtaz. For instance, carnelian came from Arabia, jade from China, jasper from Punjab, turquoise from Tibet, lapis lazuli from Afghanistan, and sapphires from Sri Lanka. In all, some 28 types of gemstones were used as inlay.

Common Gems in the Taj Mahal

It’s said the lapidary artists decorating the Taj Mahal chose stones “whose luster and color never fades.” Here are just a few:

• White, yellow, and black marble
• Blue lapis lazuli
• Red and orange carnelian
• Green jade
• Blue turquoise
• Jasper in varied colors
• Green malachite
• Green-and-red bloodstone
• Multi-colored banded agates and chalcedonies
• Garnet
• Sapphire

In addition to flowers, inlaid calligraphy composed of jasper and black marble graces several parts of the Taj Mahal, particularly recessed arches. The calligraphy highlights passages from the Qur’an that were chosen by the Persian Abdul Haq, who was greatly admired for his skill as a calligrapher. He used an elegant cursive style known as “thuluth script.” Shah Jahan graced him with the title “Amanat Khan Shirazi” for his work. Such was the attention to detail that calligraphy in higher parts of the building is slightly larger to reduce “skewing effects” when viewed from the ground. Everything about the Taj Mahal had to be pleasing to the eye with balance, symmetry, and harmony.

Taj Mahal Through the Years

Shah Jahan was a rich man with a rich kingdom and as such could afford inlay using the best of precious and semi-precious stones. However, if you were a ruler in a province lacking in resources but you at least wanted to look rich, you had plaster painted to look like inlaid marble or plaster inlaid with colored glass and mirrors simulating gemstones and silver. But, try as they may, none came close to replicating the real deal at the Taj Mahal.

Decorative elements in the Taj also once included gold and silver, including a gold spire atop the main dome. But Agra was invaded in the 18th century by armies of the Jat rulers of Bharatpur. They took away all gold and silver elements, as well as an agate chandelier. At some sites, all precious stones had been pried from walls and it is said that invading armies would pile wood in halls and set it ablaze to capture silver as it melted and dripped to the floors. In light of such carnage elsewhere, we are lucky the Taj Mahal escaped further vandalism over the many centuries.

By the end of the 19th century, the Taj Mahal complex had fallen into a state of disrepair. Recognizing the significance and beauty of even a tarnished Taj Mahal after India had been colonized by the British, viceroy Lord Curzon embarked on a restoration project that was completed in 1908. Despite ups and downs, India and the world continue to recognize and appreciate the beauty, symmetry, and significance of this incomparable gem of love, loss, and paradise. In the words of the poet Rabindranath Tagore, it will forever stand as “a teardrop on the face of eternity.”

Explore More

• Official website of the Taj Mahal: www. tajmahal.gov.in/

• UNESCO Taj Mahal profile: whc.unesco.org/en/list/252

• Explore the Taj Mahal: www.taj-mahal.net/newtaj/textMM/Inlay.html

This story about Taj Mahal gems previously appeared in Rock & Gem magazine. Click here to subscribe. Story and Photos by Jim Brace-Thompson.

The post Exploring Taj Mahal Gemstones first appeared on Rock & Gem Magazine.

When the war ended, mines powered down, leaving countless miners jobless, miners who knew the underground workings and minerals without an opportunity to use their skills. Surplus war materials like Jeeps were sold and military veterans, among others, combined the availability of four-wheel-drive vehicles with the opening of more federal lands and headed into the great outdoors, and the mineral collecting hobby grew rapidly. This rapid growth created a ready market for minerals, which prompted Mexican miners to go back to work, with some even forming mineral collecting consortiums.

Mexican Rocks & Minerals in High Demand

Instead of mining metal ores, the miners mined mineral specimens of every variety. Mineral dealers located close to the border became a ready market for access to minerals from Mexico. As miners realized they could make a living underground, the flow of minerals from Mexico’s mines became a flood by the early 1950s.

The volume of minerals coming out of Mexico was so great that some dealers became wholesale marketers operating in or near border towns like El Paso and Tucson. This interest provided Mexican miners a ready outlet for their efforts. In a short time, dealers and collectors began driving to Mexican mining towns to buy directly.

Wholesale dealers like Tucson’s Susie Davis sold minerals by the flat and never lacked good stock. Miners catered to visitors but always kept the better specimens under the bed. People who visited the Tucson Show by 1960, especially show dealers, planned ahead and drove to Mexico after the show to restock.

Today, with the growth in illegal activities and a slowdown in mining, the halcyon days of rockhounding in Mexico are more past than the present. Solo trips are less encouraged than in years past.

Mina Ojuela

In spite of some difficulties collecting in Mexico today, there are still plenty of fine Mexican minerals available, which is a testament to the huge quantity of specimens that poured forth in the last half of the 20th century. Miners are still working underground, and once in a while, a big hit happens.

Among the most active mines during the heyday was Mina Ojuela, Mapimí, Durango. It is credited with producing some of the world’s finest examples of species like adamite, legrandite, and koettigite. It soon became the darling of Mexico’s mineral business 50 years ago, along with Santa Eulalia, Zacatecas, and San Luis Potosi. There are several mines around Mapimi, but Ojuela was the first in the Durango area. Over time, underground tunnels eventually interconnected the mines, so a miner might be digging in one mine but credit his find to Ojuela often to keep secret where he actually found the minerals.

Mina Ojuela’s Specimens

Mina Ojuela was discovered in 1598 by Spaniards looking for riches. The ore vein they spotted was high on the wall of a limestone canyon, which created a problem. Reaching the ore was tough enough, but to actually mine the ore presented a major elevation challenge and an amazing feat of effort.

Mina Ojuela’s reputation as a specimen producer is due to the number of species it produced. The variety of species reads like the index of a mineral book. Until Mina Ojuela, adamite was a non-descript hydroxide zinc arsenate of modest color and crystal size.

The type locality was Chañarcillo, Chile. The ancient silver at Lavrion, Greece, produced decent adamite as well, but it was not until the brilliant green crystal sprays of adamite from Mina Ojuela came out in huge quantities that adamite was a must-have mineral. Its crystals are in a fan-like shape or fat ball-like crystal clusters, single crystals and sprays all on a contrasting dark brown iron oxide matrix. The quantity found here was astounding.

Another mineral found at Mapimí is olivenite, hydrate copper arsenate. The only difference between olivenite and adamite is the metal within; in one, it’s copper, and the other, zinc, which are compatible and can easily replace each other. Adamite is green thanks to a trace of copper in it. When copper replaces even more zinc, it is cuproadamite. Russian scientists went further in 2006 and found that if enough copper replaces zinc in some cuproadamite, it forms a new species, zincolivenite. Is your cuproadamite really zincolivenite? Ask Mother Nature.

Mexican Rocks & Minerals

The specimen-producing mines of Mexico are all known. The Spaniards started them out as silver mines and some produced wonderful silver sulfosalt minerals like acanthite, polybasite, tetrahedrite, tennantite and bournonite, all collector minerals. These same mines did not gain a reputation for producing native silver specimens except for Batopilas mine, Sonora. The vast majority of the silver mines had the metal argentiferous galena, sulfosalts, and other collector minerals in the deposits. These old Spanish silver mines became major sources of fine collector minerals for decades in the 20th century as local miners became skilled mineral specimen miners.

The Batopilas mine, Chihuahua, produced fine native silver specimens in some quantity when opened in 1632 by the Spaniards, who found the local native people working it. Even today, this mine is known among collectors for its fine twisted wires and crystals of silver. Spaniards were only interested in mining the silver, so other minerals were bypassed, leaving them for collectors who followed.

Sonora & Chihuahua

Each of Mexico’s states is known for a particular mineral species. Sonora is famous among the lapidary crowd for agate. Among collectors, wulfenite from Sonora and nearby Chihuahua is well known. Chihuahua was made famous by National Geographic in 1921 when it featured the giant selenite crystals in the Cave of Crystals/Cave of Swords. It revisited the site again in the 1990s. This second visit was broadcast on television as the selenite cave had the world’s largest selenite crystals — 40 feet long!

Zacatecas & San Luis Potosi

The state of Zacatecas has certainly produced superb collector minerals including azurite, galena, sphalerite, chalcopyrite and other metal ores. And, of course, silver species and gold have also come from here.

San Luis Potosi is very well known among collectors due to the superb poker chip calcite specimens it yielded in recent years. These specimens rival the historically important calcites from Germany. Quantities of large and sometimes colorful danburite crystals still come from here now and then as well.

Sinaloa

In recent years, Sinaloa really caused a stir among collectors when the mine at Choix produced large quantities of colorful botryoidal smithsonite. Specimens up to a foot across were mined, and the color range seemed endless, from white to pink to yellow, blue, and green in various tints. Many of the Chiox smithsonite was easily mistaken for the famous blue specimens from Kelly Mine, New Mexico.

The range of collector minerals from Mexico in the last 75 years is simply amazing. From gorgeous Las Vigas amethyst crystal groups to recent Milpillas mine azurites to rare silver sulfosalts and everything in between, these finds enhance mineral collections worldwide.

The millions of mineral specimens brought to grass in Mexico have played a huge role in the growth of this hobby throughout the world in these last decades, and there is no end in sight.

This story about Mexican rocks and minerals previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Jones.

The post Mexican Rocks & Minerals Collecting first appeared on Rock & Gem Magazine.

What is the Schiller Effect?

The Schiller effect occurs when light shines into a translucent mineral containing thin layers or platelets of metals. The light gets diffracted and sends out colorful shimmers.

Forged by Earth’s Fire

Fire agate started thanks to fire within the Earth. A group of volcanoes came alive between 36 and 24 million years ago. They spewed fire-hot lava. As it hardened, it cracked and formed crevices and pockets that became permeated with groundwater. That water remained very hot thanks to magma beneath the surface, and it was rich in minerals. These minerals settled in layers within the crevices and pockets. The result? Fire agate!

Found In Few Places on Earth

While agate, in general, is very common, fire agate is very rare. It is found in just a small corner of the world: the American Southwest (New Mexico, Arizona, California) and north-central Mexico. Sometimes you find it loose on the ground after it weathers free from volcanic rocks, but more often you need to dig, then pry it out with rock hammers, chisels, and pry bars. Even dynamite! Several mines have opened, and some allow amateur collectors to enjoy the strenuous labor of hard-rock mining for a fee.

A “New” Member of the Gemstone Family

While most major gemstones have been found and crafted for hundreds or thousands of years, fire agate is said to have been discovered only in 1939 in southeastern Arizona. It wasn’t until the mid-1940s that it started to be mined in any quantity and then introduced to the gemstone marketplace. At Mohs hardness of 6.5 to 7, it is durable and takes a fine shine. In other words, the perfect gemstone!

This Rare Gem Requires a Master Crafter

Crafting the perfect gem from fire agate takes the special care, attention, and utmost patience of master lapidary artists. They grind away the chalcedony to get close to the iron oxide layer. When ground to just the right level and polished, iridescent “fire” seems to leap from the stone with flashes of red, orange, yellow, green, bronze, and/or highly prized purple and blue. To get to the shimmering layer, you need to proceed slowly and carefully. Lapidary artists constantly evaluate as they go under bright light. Sunlight is best.

Common Pitfalls in Working With Fire Agate

The best lapidary artists follow the contours of the bubbly Chalcedony when cutting into and grinding a fire agate. They employ a combination of rock saws, grinding wheels, handheld tools such as Dremels or Foredoms, and rock tumblers to get the most uniform shine that brings out the best shimmer. Along the way, they try to avoid several pitfalls:

• Not grinding away enough chalcedony dulls the fire.

• Grinding away too much and cutting into the iron oxide layer destroys the fire.

• Applying too much pressure when grinding overheats and cracks the stone.

• Grinding the stone flat rather than following the botryoidal contours results in some areas of great fire but other areas that are dull.

Fire Agate Lore & Legend

Because fire agate is a relatively new player in the gemstone world, there are no ancient legends associated with it. Arizonans once considered it their unofficial state mineral. (They have since designated wulfenite and turquoise as the official state mineral and gemstone.) New Age mystics consider fire agate a “protection stone” to deflect negative energies. Some New Agers call it “the spiritual flame of absolute perfection.” A spiritual flame it truly is!

This story about fire agate previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Jim Brace-Thompson.

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Chalcedony

The general term, chalcedony, refers to varieties of quartz where microcrystalline and cryptocrystalline crystals intertwine and grow together. There are many varieties of chalcedony in different colors and patterns. They are plentiful and popular. Gem-grade chalcedony is generally light blue, white or gray and often called holly blue. Chalcedony’s name is said to come from the Greek port of Chalcedon.

Varieties of Microcrystalline Quartz

Agate – Curved banded variety

Jasper – Opaque, red or green varieties

Chert – General name used for compact, hard rocks that contain microcrystalline quartz

Flint – Afiner-grained, harder type of chert, Ohio’s official gemstone

Carnelian – Orange-red opaque mineral

Onyx – Parallel banded variety

Sardonyx – Red sard and white chalcedony

Chrysoprase – Translucent, apple-green color

Bloodstone – Dark green with red spots of iron oxide

Petrified Wood – Over time chalcedony replaces wood while preserving the growth rings

Happy Micro Quartz

Microcrystalline quartz has so many beautiful varieties that it’s often interwoven into our pop culture. It’s a happy birthday for these micro quartz birthstones – bloodstone (May) and sardonyx (August). Chalcedony itself is said to bring stability and balance to its bearer.

This story about micro quartz minerals previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Richard Gross and Pam Freeman.

The post Micro Quartz Mineral Basics first appeared on Rock & Gem Magazine.

Buying & Picking Material

Even though Mexican lace agate isn’t readily available, it can still be found in online sales or at shows. When picking out material to slab, you can see how the patterns will look from the outer sides of the rough. The rough may vary from tightly compressed sagenite lines to many open drusy vugs. Most of the material that I have encountered has been stable and fracture-free, but with all stones, there are still chances of finding fractured material. Just look carefully before buying.

When starting to slab the stone, look for the side with the best patterns and directional patterns that you like best. There’s a good chance, you will only cut maybe a slab or two, before wanting to pull the rough out and reposition it in the saw and try from another side. With each slab cut, the patterns and direction of the patterns will completely change, so it might be best to experiment with cutting from different sides to find what you like best.

Preform & Cabbing

When starting to draw out preform shapes, give an extra 1mm of space around your design, as this material tends to be a bit delicate around the edges and can chip on the coarser grit wheels. This will leave extra room to fix what might be lost to a chip.

As with most agates, most people start off on an 80-grit steel wheel, but with this material, I would suggest using a broken-in wheel, and not one that is brand new, as it will chip the edges. I would suggest using the 80-grit to shape somewhat close to your drawn-out lines and then graduating to a 60-grit soft resin wheel to finish shaping the edges. You can go back to the 80-grit to dome the top or take a little extra time and do it on the soft 60-grit wheel.

From this point, you can use a soft 140-grit, which would help to speed up production or go to your 280-grit soft resin wheel. This is where you want to take your time and make sure all the scratches are out. There is one very big pitfall. White stones are the hardest to see scratches in, especially if they have sagenite patterns. One thing you can try is to quickly jump to your 1200 soft resin wheel and run your cab over that for a minute. It should show you any/all the scratches that are still left.

If they are all gone, consider that finished at the 280-grit stage and move on to your 600-grit wheel. From this point, this material will still look dull, but don’t let that fool you. It will start to show a dull shine on the 1200-grit stage. I usually finish up on either an 8k-grit soft wheel or step it up a notch for a more mirror finish on the 14k-grit wheel. Just be careful. Even on the fine polishing wheels you can still crack or fracture a vug that’s close to the edge of your cab.

For most people, finishing on the wheels will leave a beautifully desired polish. For those who want to obtain a super glossy mirror finish, you can use either cerium oxide on a leather buffing wheel or Zam polishing compound with a felt tip on a Dremel or a foredom tool.

This story about mexican lace agate previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Russ Kaniuth.

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Quartz has long been the cornerstone of the gem and lapidary industry, especially as druzy gemstones. It is also popular in the collecting hobby. We would be hard-pressed to find many people who don’t have some variety of it in their collections.

Knowing how to identify quartz is important. This mineral has a relatively simple chemical structure. It is made of an atom of silicon (one of Earth’s most common elements) and two of oxygen (its most common element). Together, they form molecules that take the shape of a tetrahedron, rather like a pyramid with one corner pulled out to distort the whole. These, in turn, attach in a spiral fashion, forming beautiful hexagonal crystals that usually have pyramidal, or pointed, terminations.

Quartz Formation

If the quartz approaches pure silicon dioxide, it is clear and colorless, with air bubbles and miscellaneous impurities accounting for the milky hue often seen in quartz. Types of inclusions in quartz — other metal ions such as iron or aluminum — can become part of the internal arrangement, giving the potential for color.

When atoms combine to form molecules, they usually do so by sharing electrons, bonding them together. If everything balances electrically, the atom is stable and neutral. But when aluminum is present in quartz, it replaces some of the silicon atoms, and they differ in their electron balance. Silicon shares four of its electrons with two oxygen atoms in rock crystal. Aluminum, taking the place of silicon, has only three electrons it can share with two oxygen atoms. This electron difference makes the quartz susceptible to outside energies. Introduce a bit of radioactivity, and the quartz containing aluminum becomes a smoky color — one of the most popular varieties of quartz. We can make smoky quartz by bombarding clear quartz with radiation, something often done with Arkansas quartz.

Iron is another metallic element that can get into the atomic structure of quartz and affect the color. Iron is unusual because it can have four electrons to share, like silicon, or it can have only two or three, like aluminum. If it shares three electrons, the quartz can take on a yellow color. We call that citrine. If the iron has four electrons to share due to an unusual case of radiation, it will take on an amethyst (purple) color. We can change amethyst to citrine by heat-treating the quartz to disturb the electron arrangement.

The final color we see in crystallized quartz — the least common of the group — is rose. Various research has shown that the reason for the lovely, limpid pink color may have to do with the presence of titanium. Additionally, the Gemological Institute of America reports, “Research has shown that rose quartz owes its delicate pink color to microscopic inclusions of aligned silicate mineral fibers.” Again, the interaction of electrons produces the color emissions we see.

As you know, there are other colors of crystallized quartzes: green and blue, among others. These colors are largely due to inclusions, though citrine and amethyst quartz, as I mentioned, can be changed to green by heat-treating the stone.

Family Structure

The other quartz family of minerals falls under the heading cryptocrystalline quartz, a name that simply means it forms in crystals too small to see without magnification. That definition is a bit of an oversimplification, given that the submicroscopic crystals are fiber-like in most cases.

This variety’s main form is chalcedony, followed by agate, jasper, carnelian, sard, heliotrope, and onyx, among others. Within this grouping, there is a division. The agates are fibrous in structure, while jasper and flint are grainy quartzes.

Chalcedony is a particularly appealing gem material, as it is hard and easy to work and can come in a rainbow of colors, depending on impurities. The forms of iron in chalcedony color it red, yellow, orange, or brown. Copper minerals impart a blue shade, while nickel makes it green. Its formation mode can produce lovely alternating layers of colors that can be wildly patterned in bands, swirls, dots, and eyes. It is this multicolored, patterned chalcedony that is most popular with the lapidary.

Agates’ Quartz Foundation

The history of agate as a gemstone is longer than almost any other gem. It was gathered from streams in ancient times and used for jewelry. By the time the Romans controlled the world, the first great agate beds were being exploited around Idar and Oberstein, Germany. A huge agate gem business evolved there, outlasting the Roman and succeeding empires until the local supply dried up. At that point, German emigrants went searching for new supplies, and the great agate fields of South America opened.

For the most part, the Brazilian agate fields produce gems that lack bright colors. But agate is porous enough to be treated with heat or dyes to produce lovely, banded material; since each layer of chalcedony agate varies slightly in porosity, the dyes are selectively absorbed.

In the 1940s, one of the great sources of agates, naturally colored in a riot of hues, was opened up in northern Mexico. This material ranks as some of the better agate ever found. The source was volcanic formations, primarily in the state of Chihuahua. The agates here are so beautiful that they require special attention in an article such as this. The only problem today is availability.

Seventy years ago, Mexican fortification agates were readily available and possible to collect for the adventuresome. By 2001, the large beds of Mexican agate were nearly played out or closed to collecting. Where agates may still be found, they must be hard-won from the enclosing volcanic rock and can be hunted only with permission.

There are several agate beds in Mexico. The agates are often named for the source of locality, with Laguna, Coyamito, Gallego, Sueco, Apache, and Apache Flame agates among the best known. There are countless other sources of agate in Mexico, but these areas are the most notable. Gem material from each of these areas is distinctively colored and stunning.

What I like most about Mexican agates are the internal patterns they contain. Each stone is unique. Some are strictly fortification agates, with a series of concentric bands of varying width and color, yet with a pattern uniformity. Others have concentric rings of color with a point in the center, which is why this variety of agate is called “eye agates.” These eyes develop when internal, stalactitic growths in the agate are cut across the grain. If cut along their vertical axes, the pattern consists of two parallel bands of matching colors, slowly tapering to a rounded point. Some of the eyes have a small, hollow tube in the center where solutions may have entered or where some slender, needle-like crystal, now gone, gave rise to the stalactite form.

Scattered within many agates are color dots and streaks. Some are large enough to be seen with the unaided eye. Most are best seen under 10x magnification as bright dots or spots or colors that give the band’s overall color shade. These small concentrations of color have been shown to be largely iron compounds, with some manganese compounds as a second color source. In a few cases, snow-white dots are seen, which are usually bits of colorless quartz.

The fascinating feature of many agates is the “escape tube.” This is a bulbous shape that starts within the banding and extends toward and sometimes to the agate’s rim. These tubes are sometimes narrow in the center with a bulging tip. If they touch the rim of the agate, they spread out in a funnel-like form.

For a long time, these escape tubes were thought to be the avenue through which the silica solutions entered the hollow geode or gas pocket in lava. These solutions were credited with creating the banding for which these agates are prized. However, modern studies have shown that the reverse is actually true.

The elongated structures actually are escape tubes. As the agate formed from a silica gel material, increasing pressure caused the remaining solutions to probe and penetrate the agate layers that had already formed at their weakest point. This movement to reach the rim of the agate so as to relieve the building pressure caused the existing, fresh layers to be dragged toward the flow of the escape. So, when you look carefully at an agate with an escape tube, you can readily see the distorting effect this movement has created. The regular fortification pattern is pulled like taffy into unusual and irregular forms. All of this adds to the internal beauty of that agate. Couple that with a nice quartz crystal lining in the center of the agate and you have something quite attractive.

One of the most beautiful quartz forms used in jewelry is quite valuable, even though the quartz is an ordinary milky white. Of course, the fact that it has stringers and veins of gold running through it may account for its higher-than-usual value. Called “gold in quartz,” this lovely material is contrasting snow-white and rich, buttery yellow. It can be slabbed and polished, then used as cabochons, for beads, or as an inlay gem material, among other uses. Set in rings and brooches, it is an instant conversation piece, and when used to make jewelry boxes and ornamental objects of art, it is quite elegant. Much of the “gold in quartz” comes from California’s mines, though it may be expected any place gold occurs in white quartz veins.

As long as people collect gems and minerals, there is going to be an attraction to quartz. Many collect only that singular species, which is understandable, given that there are myriad sources the world over. It comes in a great variety of wonderfully showy crystallized forms and in several attractive colors. The massive varieties can be riotously colored and patterned agates or richly colored solid gems suitable for jewelry making. No wonder quartz is and always will be one of the most popular minerals.

This story about the quartz mineral group previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Bob Jones.

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