Although most people know this material for its beautiful blue color, it also can be found in pink and violet. Dumortierite can be found in various places across the globe, and at times, has been mistaken for sodalite, or lapis lazuli. Some variations that have gorgeous fibrous dumortierite sprays inside quartz crystals are rare. These tend to be very small pieces, usually ranging from one to five carats. Dumortierite is a good material for lapidary beginners to get hands-on experience. It’s available almost anywhere rocks are sold in a good variety of colors and patterns. It’s fairly hard, usually about seven to eight on the Mohs scale. It also cuts fairly easily.

Tips for Buying Dumortierite

When buying Dumortierite rough, the colors usually show on the outside, but it can have a thin brown rind that can be chipped away to expose the inner color. Many times the blues can be mottled with a lot of white. If a certain hue of blue or continual color throughout is needed, it’s best to buy slabs to be certain.

Cutting Rough Dumortierite

When starting out cutting rough, there is no certain direction to load the saw. This is helpful so that it can be loaded in a way that best fits the vice and yield the most material by cutting straight across the entire stone in one direction. Once the slabs are cut, there generally aren’t many fractures in this material. However, it’s always best to bench test before marking up the slabs for preform designs. Either flex the slab in hand to see if it’s stable or lightly tap it against the workbench or ground to see if there are any hidden fractures. This helps to avoid breaking while in the middle of trimming out cab shapes.

Cabbing Dumortierite

Once the preforms are cut and ready for cabbing, be sure to have a dry towel or canned air available to check for scratches along the way. Since towels get damp in a hurry and canned air can start getting expensive, one suggestion is to get a five-gallon air tank with a spray nozzle. It can be continually filled up by a personal air compressor or by a nearby gas station and it will last for quite a while.

Dumortierite tends to quickly show heavy white marks if scratches are still present. I suggest starting on an 80-grit steel wheel to shape and dome cabs and moving to either a 60-grit soft resin wheel or 140 soft resin. This material is fairly hard, so it will take a bit of time to smooth it out and remove all the scratches from the 80-grit wheel. Be sure to dry off occasionally and see if any white scratches are showing.

From this point, move on to the 280-grit soft resin wheel. A white or pale blue haze across the cab is to be expected, but not scratches. Make sure no scratches exist before moving forward. From this point, it’s fair routine to continue cabbing to the 600 grit, all the way up to the 14k grit soft resin wheels.

Finishing Gloss

A 50k grit polishing wheel works great to get an added high-luster gloss. Unless going slow in short increments, it’s not suggested to use polishing compounds on this material. Also, be sure not to allow the material to heat up too much. It can tend to fracture with heat.

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

The post Dumortierite: What to Cut 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.

The Start

In 1935, a Depression-era government works program allowed the Milwaukee Public Museum (MPM) to continue operations and provide much-needed jobs to local unemployed workers. These new employees spent their days preparing the Museum’s Earth Sciences displays. In the evenings, they held meetings in their homes to learn more about the rocks, minerals, and fossils.

With the MPM offering use of its Trustee Room for meetings and the Milwaukee Journal providing publicity, the non-profit Wisconsin Geological Society was formed in early 1936.

Branching Out

The newly-found box revealed how active the WGS was in building a solid foundation for its club and also for clubs across the country to connect. For instance, in 1940, the WGS was one of three clubs involved in the creation of the Midwest Federation of Mineralogical and Geological Societies (MWF). In 1950, WGS members were among the eight delegates to the first American Federation of Mineralogical Societies (AFMS) meeting held in Salt Lake City.

In 1984, the Wisconsin Geological Society hosted a large joint rock and mineral show with the MWF at State Fair Park in West Allis that resulted in a 36-page document outlining all the activities including field trips. Joint shows were previously held in 1941, 1944, and 1954.

Blackjack Bonanza

Corn dogs, cotton candy, amusement rides, and a lead/zinc mine tour? Yes!

From 1963 to 1966, Blackjack Bonanza mine tours were a re-creation of a real lead/zinc mine at the Wisconsin State Fair. It was a 15,000-square-foot exhibit that sported a 65-foot headframe tower, an elevator shaft that shook to simulate the ride down into the mine tunnel, and a 30 by-45-foot processing room. A hidden 50-ton A/C unit cooled the mine tunnel making guests think they were far below ground. Mine tours cost fairgoers 75 cents per adult and 24 cents per child.

Like other fair attractions, the Blackjack Bonanza became a part of history as well as the role the WGS played in its existence.

The box revealed that in 1966, members of the WGS took over the 10-day, 12-hour per day, operation of the Blackjack Bonanza mine tours. Club members provided ticket sales, tour guides, and mine workers. They also provided mineral samples for a museum display as well as staff to operate the gift shop.

Naming the Wisconsin State Fossil

State fossils are nothing new. Lots of states have them. But through the box and personal interviews, WGS members found out that club members played a significant role in the process for their state. It took three attempts before the trilobite (Calymene celebra) was officially named Wisconsin’s State Fossil in 1986.

The first attempt was made in 1981 by a UWM geology student, Mark Shurilla, but he neglected to name a specific species of trilobite. The bill failed.

Wisconsin Geological Society members picked up the process in 1983, narrowing the field to the Calymene celebra, found primarily and prolifically in Wisconsin. Again, the bill was defeated.

In 1985, at the direction of the WGS Board of Directors, club president, and chief lobbyist for the bill, Margaret Pearson, made a final and successful attempt. This time, the bill was sponsored by State Assembly member, Jeannette Bell, daughter of WGS members Harold and Luella Jeske. Members of WGS were present at the bill signing on April 2, 1986, in Madison, Wisconsin, as Margaret presented Governor Anthony Earl with a trilobite specimen to mark the occasion.

More Fossils

The original Milwaukee Public Museum opened its doors to the public in 1898. It now houses the Milwaukee Public Library. The board room where the first official WGS meeting was held still exists and is on the National Register of Historic Places.

In 1975, the Museum moved to a new facility across the street but did not have enough room for all of the geology exhibits, including fossils that WGS members originally displayed in 1936.

Fundraising is underway for a new facility with a groundbreaking scheduled for late 2023. It should be open to the public sometime in 2026. It will be a representation of ancient sea stack formations present in Wisconsin’s Mill Bluff State Park. The rounded edges of that building will showcase the glacial weathering that formed Wisconsin and deposited those fossils. Inside, will be displayed those original WGS fossils from 1936.

Plan, Collect, Verify & Store

While the plastic box brought history to life for WGS members, they soon found out its information was incomplete and that members had bits and pieces of history in lots of places; old newsletters here, photo books there. Records ended up in various places as officers and leadership transitioned over time. The club historian, and volunteers, made a plan to gather all of the documents. Here is a to-do list for other club historians that may have the same circumstances.

• Scan and identify all photos and documents and create a digital file

• Contact club officers, new and old, for any information in their possession

• Contact outside sources to verify and provide additional information

• Create documents and a presentation to share with members

• Develop a storage plan to preserve past, current, and future records

After collecting information from members, the first critical step for the WGS was to scan and identify photos and documents and place them in a digital file, backed up on a memory stick.

Finding More Photos

Next, was to contact club officers and members to see if any files or pictures had been handed down to them. Also, an article was published in the club’s monthly newsletter, The Trilobite, asking members who are no longer able to attend meetings to offer any information or photos.

Early on, Wisconsin Geological Society members took field trips, attended study groups, participated in mineral shows, and enjoyed parties and picnics just like they do today. One of the early members must have been an avid photographer as many of these functions were captured with lovely photos. The documentation and preservation of those photos were poor. Names of members and photo locations were often missing or destroyed the photograph by writing or gluing a note directly on the photo.

An Interesting Photo

One of the most interesting photos in the collection was of young boys, wearing knickers, admiring the rocks and minerals in a Wisconsin Geological Society display case. The photo had a typewritten note paper-clipped to it, “Hobby Show November 24-27, 1950?” A scanned copy of this photo was emailed to the Milwaukee Public Library (MPL) archives department for verification. They were able to confirm that a hobby show was held from November 24 to 27 in 1949, however, they could not verify that this photo was taken at that show. According to historical fashion records, knickers for young men had gone out of fashion in the late 1930s.

Photo identification is important. Always record the following information:

• Event

• Place/location

• Date taken

• People, use an easy format of left to right (L to R) and rows top to bottom

• Photographer, if possible

Community Help

Research to fill in the missing information became the next priority. Organizations whose history crossed the club’s path came first. Historical societies and newspaper articles provided another great resource.

Some sources responded immediately, while others required a longer response time. The most successful recoveries of information resulted from telephone calls which produced a real person contact. Additional details continue to be added to the club’s historical records as a result of these contacts.

Long-Term Storage

After a huge effort to gather all of this history, it became important for the WGS to change how it gathers and stores its data in the future. The Milwaukee Public Library has worked with club members to develop a plan for the WGS to donate its current historical records and future yearly updates. Current and future WGS members will retain access to all of their records during normal library business hours.

This story about the Wisconsin Geological Society’s history appeared in Rock & Gem magazine. Click here to subscribe. Story by Sue Eyre.

The post Wisconsin Geological Society History first appeared on Rock & Gem Magazine.

A few prospectors did indeed make their fortunes. Still, most received their reward by participating in an adventure that thrilled the nation and introduced words and terms like “radioactivity,” “Geiger counter,” and “radiometric prospecting” into the general vocabulary.

Although finding a million-dollar uranium deposit today is unlikely, understanding radioactivity and knowing how to detect it can greatly enhance the mineral-collecting experience. Radioactivity is one of the fascinating physical properties of minerals. It is ionizing energy in the form of particles and rays produced by the spontaneous disintegration or “decay” of unstable atomic nuclei.

Understanding & Identifying Radioactivity

While this definition might seem a bit intimidating, getting a practical handle on radioactivity is not that difficult. Admittedly, the word is loaded with negative connotations linked to nuclear weapons, fallout, toxic waste disposal, reactor meltdowns, and the hazards of radon gas. Nevertheless, radioactivity is very much a part of the natural world, especially the world of mineralogy.

Minerals are described as radioactive when they emit energy in the forms of alpha, beta, or gamma radiation. “Radiation” is the catchall term for energy in the form of waves or particles. Gamma rays make up the extreme high-frequency, shortwave end of the electromagnetic spectrum, broadband of radiation energy that includes radio waves, microwaves, infrared, visible light, ultraviolet, and X-rays.

Alpha and beta particles are not forms of electromagnetic energy. Alpha radiation refers to positively charged, high-energy, low-mass particles that consist of two neutrons and two protons (the nuclei of helium atoms). Beta particles can be negative or positive; negatively charged beta particles are high-speed electrons, while positively charged beta particles are positrons (the “antimatter” counterparts of electrons).

Exploring Ionization

Alpha particles, beta particles, and gamma rays (along with X-rays) are classified as “ionizing” radiation, meaning that they have sufficient energy to ionize atoms in the materials they strike. Atoms become ionized when they lose electrons and assume a net positive charge. Because it disrupts normal biochemical functions on the molecular and atomic levels, ionizing radiation can be harmful to living tissue. Ionizing radiation is produced by nuclear fusion, nuclear fission, and atomic decay, the latter being the natural disintegration of the nuclei of unstable, heavy elements or isotopes (elements with different numbers of neutrons).

Ionizing radiation can be cosmic, man-made, or geophysical in origin. The sun, a giant nuclear fusion furnace that emits intense gamma radiation, provides most of our cosmic radiation. Fortunately, very little reaches the Earth’s surface because of its distance from the sun and atmospheric absorption. During the past 80 years, the Earth’s cumulative environmental radiation load has increased significantly due to uranium mining and processing, nuclear weapons manufacture and resting, nuclear power and X-ray generation, accidental radiation releases, production of radioactive isotopes for medical and industrial uses, and radioactive waste disposal.

Geophysical Radiation

Mineral collectors, rockhounds, and prospectors are most interested in geophysical radiation, which is emitted by natural radioactive elements that are present in minerals as essential or accessory components. Most geophysical radiation is produced by uranium and thorium, which occur in trace amounts in many igneous rocks, especially granite. The effects of geophysical radiation go far beyond surface radioactivity. An estimated 80 percent of the Earth’s internal heat is produced by the atomic disintegration of uranium, thorium, and the elements and isotopes in their atomic-decay chains.

Of the 92 naturally occurring elements, 11 are radioactive. Of these, only uranium and thorium are relatively abundant. Uranium was identified as an element in 1789; it was isolated in 1841 as a very dense, silvery-white metal that oxidizes rapidly in air. Ranking 51st in crustal abundance, uranium is about as common as tin.

Thorium, discovered in 1828, is similar in appearance to uranium but is half as dense and much more common. Until the discovery of radioactivity, uranium and thorium were little more than laboratory curiosities. Small quantities of uranium oxides were used to color glass yellow, while thorium compounds that incandesce (emit visible light) when heated were employed in gas-lantern mantles.

Driven by Discoveries

The discovery of radioactivity followed investigations into the mysterious, penetrating “invisible energy” that was produced by passing an electrical current through vacuum-discharge tubes. In 1895, the German physicist Wilhelm Conrad Röntgen (1845-1923) named this energy “X-rays” to signify its unknown nature. Radioactivity was accidentally discovered in 1896 when French physicist Antoine-Henri Becquerel (1852-1908) studied the effects of X-rays and sunlight on potassium uranyl sulfate, a compound that fluoresced in direct sunlight. Becquerel placed this compound atop photographic plates wrapped in lightproof black paper, then exposed it to sunlight.

He noted that the photographic plates became exposed and attributed this to some type of penetrating energy related to fluorescence.

When cloudy weather delayed his experiments, Becquerel stored both the uranium compound and the unexposed, wrapped photographic plates together inside a dark desk drawer. Later, out of curiosity, he developed the plates and found they had already been exposed. This exposure meant that the uranium compound—without any induced fluorescence—continuously emitted invisible, penetrating rays. Becquerel then demonstrated uranium itself, not its compounds, was continuously emitting these rays, which became known as “uranium rays” or “Becquerel rays.”

Marie Curie & Ernest Rutherford

Among the first to investigate these rays was Marie Curie (1867-1934), the Polish-born French chemist and physicist who coined the term “radioactivity.” In 1898, after extracting uranium and thorium from uraninite (uranium oxide), Curie was surprised to find that the uraninite was still highly radioactive. Concluding that it must contain additional sources of radioactivity, she extracted two previously undiscovered radioactive elements—polonium and radium. The radium was particularly interesting because of its extraordinarily intense radioactivity.

In 1902, British physicist Ernest Rutherford (1871-1937) proposed that radioactivity consists of what we now know as alpha and beta particles, and gamma rays. He found that alpha and beta particles lose their energy relatively quickly as they pass through materials, while gamma rays have a far greater penetrating power. Until the discovery of radioactivity, most scientists believed that the smallest particle of matter was the atom, which was indivisible and unchangeable. But Rutherford challenged the idea of atomic indivisibility by proposing that alpha and beta particles were subatomic components of disintegrating atoms. This concept opened the door to modern particle physics and an entirely new understanding of the nature of matter and energy.

Early 20th Century Proves Progress

The early 1900s saw many exciting discoveries about radioactivity. While working with thorium, Rutherford had detected radioactivity throughout his laboratory—even after the thorium had been removed. He deduced that this radioactivity came not from the thorium itself, but from a gaseous product of thorium’s atomic disintegration. This realization led to the discovery of another radioactive element—radon.

Rutherford then postulated that radioactive elements spontaneously and continuously disintegrate to release radiation and produce a decay chain of other radioactive elements and isotopes. He also learned that radon’s intense radioactivity decreased by half every few days. His term “half-life” is now used to describe the speed at which unstable atoms undergo atomic disintegration.

Rutherford observed that an inverse relationship existed between half-life and the intensity of radioactivity. Uranium, with its low level of radioactivity, has a very long half-life of more than four billion years. But extremely radioactive elements such as radium and radon have very short half-lives. Unfortunately, the effects of ionizing radiation on living tissue were not understood. While exposure to radioactivity seemed to halt the growth of certain cancers, it also caused burns and open lesions on the skin of many researchers. Nevertheless, hopes that radiation would cure cancer and boost general well-being created a huge demand for radium, some for research purposes, but mostly to be used in patent medicines and bizarre therapeutic devices.

Mining Uranium Ore

The aspect of research triggered the first significant mining of uranium ore—not for uranium, but the ore’s tiny traces of radium. The important radium sources were uraninite from the historic Joachimsthal mines in what is now the Czech Republic and the carnotite (hydrous potassium uranium vanadate) ores of western Colorado. By 1912, radium was the most valuable commodity in existence and cost $100,000 per gram—nearly $2.5 million in today’s currency.

Initially, radioactivity could only be detected with photographic plates and fluorescent screens; it could be crudely measured with gold-leaf electroscopes and complex, piezoelectric-quartz devices. Then in 1908, German physicist Hans Geiger (1882-1945) constructed a sealed, thin metal cylinder with a wire extending down its center. After filling the tube with inert gas, he applied an electrical voltage almost strong enough to pass between the electrodes, in this case, the wire and the tube walls. When exposed to radioactivity, the gas ionized to become conductive, completing the circuit and producing an audible click. These electrical discharges instantly returned the gas ions to their normal energy level, making it possible to continuously and immediately detect additional radioactivity and measure its intensity by “counting.”

Although the first “Geiger counters” were ponderous instruments sensitive only to alpha particles, they were vital to the early studies of radioactivity. In 1928, Geiger and his colleague Walther Müller designed a new tube. Now known as the Geiger-Müller counter, it is sensitive to all forms of radioactivity and is still used today.

Greater Understanding and More Utilization

The uses, perception, and importance of radioactive minerals changed radically during World War II when uranium became the source of its fissionable U-235 isotope needed for the first atomic bombs. Following the war, the United States government subsidized the “Great Uranium Rush,” in which improved, lightweight, shoe-box-sized Geiger-Müller counters were the key tools for the thousands of radiometric prospectors who searched for “hot rocks,” mainly uraninite and carnotite. The radioactivity emitted by uranium and thorium has several effects on minerals, one of which is color alteration.

Long-term exposure to low-level radioactivity can disrupt normal electron positions in the crystal lattices of certain minerals. This activity creates electron traps, called “color centers,” that alter the mineral’s color-absorption-reflection properties. The colors of smoky quartz, blue and purple fluorite and halite, brown topaz, and yellow and brown calcite are often caused by exposure to geophysical radiation.

Metamictization

Another interesting effect is metamictization, which occurs in some minerals that contain accessory amounts of uranium or thorium. In metamictization, geophysical radiation displaces electrons to slowly degrade the host mineral’s crystal structure. Metamictization is usually apparent in crystals as rounded, indistinct edges, curving faces, and decreased hardness and density. Metamictization can sometimes completely degrade crystals into amorphous masses.

Metamictization is common in the rare-earth minerals gadolinite (rare-earth iron beryllium oxysilicate) and monazite (rare-earth phosphate). Because of their similar atomic radii, uranium and thorium often substitute for rare-earth elements to make their minerals radioactive. California’s huge Mountain Pass rare-earth-mineral deposit was actually discovered by a uranium prospector equipped with a Geiger-Müller counter.

Zirconium Silicate

Zircon, or zirconium silicate, another mineral subject to metamictization, has an additional connection to radioactivity and is employed in radiometric dating, which uses known rates of atomic decay to determine the age of ancient rocks. Because of similar atomic radii, uranium substitutes readily for zirconium in zircon. The uranium-238 isotope has an extremely long half-life of 4,468 billion years. The inert, extremely durable zircon “protects” the traces of uranium—an ideal combination for the radiometric dating of ancient rocks.

When igneous rocks solidify from magma, their contained traces of uranium have not yet begun to decay. By measuring the extent of atomic decay, geophysicists can determine when the sample crystallized. The oldest known rocks are found in Australia. Based on partially decayed traces of uranium-238 contained in tiny zircon crystals, these rocks have been dated at 4,374 billion years—only a few hundred million years after the formation of the Earth itself.

Detecting Radioactivity

Today, mineral collectors have access to a wide range of radioactivity-sensing instruments, including dosimeters that measure cumulative radiation exposure, miniaturized Geiger-Müller counters, and scintillators that quantitatively measure geophysical radioactivity, and radiation monitors that measure relative overall radioactivity. Prices for basic instruments begin at about $40, while top-of-the-line, quantitative instruments can cost thousands of dollars.

Choosing the Radiation Monitor For You

For general mineral-collecting and amateur radiometric-prospecting uses, radiation monitors, which cost from $200 to $700, will suffice. I’m familiar with the Radalert™ radiation monitor manufactured by International Medcom of Sebastopol, California. It weighs 10 ounces and contains a miniaturized Geiger-Müller tube. Alpha and beta particles, gamma rays, and X-rays ionize the tube’s gas atoms, causing the tube to discharge with tiny electrical pulses. Integrated circuits convert these pulses to liquid-crystal displays, flash light-emitting diodes, and generate audible clicks.

This instrument detects total ionizing radiation (a mix of geophysical,

cosmic, and man-made radiation) and provides relative, rather than absolute or quantitative, radioactivity measurements. It is ready for use after quickly determining the local background radiation “load,” which varies with geology, solar-flare activity, and elevation.

At sea level, the normal background radiation might be roughly 13 counts per minute. But at a mountain elevation of 7,000 feet where there is less atmospheric shielding of cosmic radiation, the background level might be 30 counts per minute. Radiation monitors can even detect temporarily elevated levels of cosmic radiation due to increased sunspot activity.

Background Radiation

Background radiation also varies with local geology. Radiation levels near granite outcrops are usually higher than in other areas because of traces of uranium within the granite. Radiation monitors can serve as a safety tool to detect elevated levels of radioactivity from potentially hazardous accumulations of radon gas in living spaces. They can also detect the very low levels of alpha radiation emitted by household smoke detectors.

Smoky quartz sometimes has detectable traces of radioactivity, while gadolinite, monazite, and other rare-earth minerals have levels that are easily detectable. When used with such uranium-bearing minerals as canary-yellow carnotite and tyuyamunite, yellowish-green-to-green autunite, and green torbernite, radiation monitors “sound off” with hundreds or thousands of counts per minute.

Among the interesting radioactive collectibles is yellow “uranium glass,” which was popular in the early 1900s and still emits detectable levels of radioactivity. Another is greenish trinitite, quartz sand that was fused together by the world’s first atomic detonation on July 16, 1945, at New Mexico’s Trinity Site. Trinitite specimens, which are still sold today, have low but easily detectable levels of radioactivity.

Proper Handling

Collecting radioactive minerals is not dangerous when precautions are followed. One rule is to collect small specimens. Cumulative radiation and the amount of radon gas emitted by radioactive specimens are directly proportional to specimen size. There is no need to collect cabinet-sized specimens of carnotite, even though they are easily found on mine dumps.

Handle radioactive specimens minimally and always wash hands thoroughly afterward. Never eat, drink, sleep or, smoke around radioactive specimens, and always keep them out of the reach of children. Also, radioactive specimens should be clearly labeled as such and stored in well-ventilated spaces away from living areas.

Radiation monitors can add a new dimension to many field-collecting trips. And they are an absolute necessity when exploring the thousands of uranium mine dumps scattered across the Four Corners regions of Colorado, Utah, and New Mexico. Radiation monitors make the difference between finding nice specimens of brightly colored, oxidized uranium minerals and finding nothing at all.

Collectors should never enter an abandoned mine, but abandoned uranium mines are particularly hazardous. These unventilated mines have accumulated extremely high concentrations of intensely radioactive radon gas.

Anyone interested in the history of radioactivity will enjoy visiting these two New Mexico museums: The Bradbury Science Museum at Los Alamos National Laboratory in Los Alamos, and the National Nuclear Museum of Science and History in Albuquerque. Both contain a wealth of exhibits and information on radioactivity—one of the fascinating physical properties of minerals.

This story about radioactive rocks previously appeared in Rock & Gem magazine. Click here to subscribe. Story & photos by Steve Voynick unless otherwise indicated. 

The post Radioactive Rocks: A Rockhound’s Guide first appeared on Rock & Gem Magazine.

This is what artifact hunting is all about – finding ancient tools, weapons and stone pieces that have remained hidden for thousands of years. These implements are often the only evidence remaining of the existence of ancient, complex and highly-functioning cultures that once thrived in North America.

Bits and pieces of chipped flint, granite, jasper and other hard rock can rise to the surface after land is plowed or following a heavy rain, indicating the likely presence of artifacts. Whether located near the water’s edge, in open fields, on mountain ridges, valleys or under overhangs, stone clues reveal locations where ancient family groups lived more than 15,000 years ago.

Artifacts Tell a Story

Granite and other rock artifacts tell the story of early human presence in every section of North America. A variety of rocks were shaped and used as tools. Flint and quartz were fashioned as fire starters. Obsidian and agate were flaked and chipped to be made into knives for blunt instruments such as axes and pestles. Hammerstones and heavier rocks, made of sandstone were ground to useful shapes and implements.

As early cultures traveled along rivers and valleys, cutting across heavily forested land, they continuously manufactured and replenished their rock instruments, chipping and grinding their tools for hunting farming, and cooking.

Hoes, hatchets, awls, drills, scrapers, and spear points as well as small projectiles were fashioned, sharpening and polishing stones, all chipped from rock carefully chosen. These chipping, flaking, carving activities remained unchanged, over thousands of years.

Before getting started, here are nine things to consider to help with finding artifacts and staying safe while doing so.

1. Get a Map

Topographical maps are a basic tool used to study ancient land areas. The U.S. Geological Survey (USGS) has been the primary mapping agency of the United States since 1879. At the U.S. Geological Survey website, you can order paper maps showing ancient forests, rivers and mountainous areas.

General-use maps present detailed elevation and contour lines to help with understanding the landscape. State or county libraries are a source for geological surveys.

Ordinance Survey maps are the best-known type of topographical map. It is possible to work out your exact location by following the contours and checking out the landscape around you, identifying landmarks such as lakes and roads. If you know a river that has remained in the same general configuration for a long time, it is a great place to find ancient rock tools since the area is likely to have been inhabited or visited over the millennia. To order any map, go to MyTopo.com.

2. List of Supplies

Things to take with you include a shoulder bag or backpack with bottled water, magnifying glass, hand digger, garden gloves, small brush and a notebook with pen as well as some sort of container with soft wrapping for any rocks you wish to keep. Carrying a fully-charged cell phone is essential for emergency and can be used for image-taking.

Remember to never go hunting alone in unfamiliar places and always let someone know where you will be.

Wear sturdy shoes or boots and a hat for protection from the elements. Carry a walking stick for climbing support, to clear debris or chase away snakes. Watch where you put your hands if you’re working in brush or rocky terrain. A few simple first-aid items are advantageous for cuts and scrapes. Keep spare clothes, extra water and extra shoes in your vehicle.

3. Permission to Search

For most places, receiving permission to hunt is imperative. Study your state laws before you begin to search; not doing so could get you in hot water with State or Federal authorities. Knowing on whose land you are hunting is essential, out of respect for both the land owner and for any original native residents.

If you are considering privately owned land, you will need permission to hunt on it. When you locate a prospective site, find out whether the land is private property. If it is, ask the owner for permission to search. Most landowners are cooperative, but if not, don’t be discouraged, just move on and keep inquiring in the general vicinity you have chosen.

All artifacts belong to the owner, unless you have permission to keep what you find. It is best to approach farmers at a time of year when the land has not been newly seeded or planted and assure them that you will cause no harm and of your appreciation for the opportunity.

4. Areas to Explore

Aside from farmland, sites off the beaten path are always worth a look, even construction sites may yield artifacts. Prehistoric people rarely camped more than a short distance from water and often chose ground that was easily defendable.

Across from what are now state lines, trails and trading paths were created, crisscrossing through forests and rivers, covering large tracts of land. Villages were not only established near river junctions, but on hillsides and valleys. Many artifacts have been found near both small and large waterways. Some examples include corner-notched spear points and fluted points as well as side-notched arrowheads.

By reading about tribes that settled in your area, you can find the most likely locations. Riverbanks, streams and dry ditches can disguise partially hidden artifacts. Dirt banks where implements may have washed off higher ground should be checked. Choose places where the ground has been disturbed or if dirt has been brought in to build or construct any housing areas.

5. Field Clues

When searching, keep your eyes open for chips of stone, regardless of color, size, coarseness or shape. Stone chips are always worth examining. What you see exposed may not be the entire piece. Although there are many stone tools to be found, such as scrapers and hoes, be receptive to the unexpected rocks that catch your eye.

It won’t be long before you develop a sixth sense about whether the rock you are holding had been held by another human hand long before yours. Small chips were further manufactured for knives, awls or gravers. Large rocks should be examined also. Pounders, some hand axes and hoes were not flaked like a typical arrowhead or knife, but were smoother and ground into shape.

6. How Deeply Can You Dig?

Federal law states that you can retrieve any artifact that is lying on the ground’s surface. If an artifact is partially exposed and easily retrieved, you are allowed to collect it. If not, you can carefully dig a certain distance around and beneath the artifact to loosen it. Protect fragile parts by bringing along an attached dirt clod. Rules regarding depth of digging may seem trivial, but they were made to protect sacred grounds, burial sites and evidence of those who lived on the land first.

7. When to Search

The best time of year to search depends on where you live. For northerners, tramping through wooded areas covered in snow would be unproductive. In agricultural areas, fall and very early spring can yield exposed stone artifacts. In western states and the deep south, the time of year may not be as relevant an issue. Check with farmers and landowners about dates and times of clearing the fields and planting seeds. Consider storms, floods and wildlife. Overall, cloudy and overcast days are best for artifact spotting.

8. Rock Types

Study and learn your location’s rock types. Some common artifact materials are quartz, chert, jasper, chalcedony, agate, basalt, granite and flint. Rhyolite is common in the southern states while quartzite is familiar in the southwest. Arrowheads were made out of anything handy, so focusing on particular rock types can lead to overlooking artifacts. Remember, the ancients travelled and traded.

9. Taking Care of Finds

Cleaning and care of artifacts is important as you don’t want to mismanage an ancient piece of art. First, wrap it in a soft cloth to keep it from knocking against another artifact. Rocks are not unbreakable, especially the tip, fashioned point or notched sides of arrowheads. It’s good to separate large pieces from delicate ones.

After returning home, wash pieces with water and use a soft brush to wash away any dirt clumps. Before washing, make sure the drain is closed so any small pieces are not lost.

Once dry, examine your findings carefully. Using an identification guide, set up a journal with columns, listing date, location where found, type of rock, probable use, time period, shape and workmanship. Write a thorough description of the rock. Give each rock an identifying number or symbol that corresponds to the name you have recorded. This is an essential part of artifact collecting and, if not followed, can cause future confusion and unhappiness.

From east to west, north and south, clues to ancient people’s existence continue to surface, and may be found anywhere in North America. Once your eye is trained, you may find artifacts at unexpected times and places, even your own backyard. Artifact hunting can become a life-long source of discovery and yield increasing appreciation of the inventiveness, survival and history of earlier Americans.

Enjoy the hunt!

This story about finding ancient artifacts previously appeared in Rock & Gem magazine. Click here to subscribe. Story and photos by Anita B. Stone.

The post 9 Tips for Finding Artifacts 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.

Quartz crystals grow when atoms of silica and oxygen lock together in a regular and repeating pattern as silicon dioxide. When quartz crystallizes, its shape connects to its nourishment, or the physical and chemical conditions surrounding it. “Perfect” or “ideal” quartz has hexagonal (six-sided) crystals with triangular faces forming pyramids on top and bottom. But perfection is the exception.

How Do Types of Quartz Crystals Misgrow?

In nature, growth conditions constantly change and crystals become distorted. One crystal face may grow faster than others. Crystals may split and develop multiple points and faces. A crystal may be twinned or intergrown with others. It may stop growing, dissolve a bit and then resume growth. In short, don’t bet on odds for a perfect crystal in nature! Inclusions in quartz are not uncommon.

1. Gwindel

Also called quendel, gedrehten or twisted quartz, gwindel (pronounced “gvin-dell”) is another collection of many stacked crystals. In the case of gwindels, each crystal seems to have formed at a somewhat curved or bent offset from the others. The result is a slightly curved comb or toothed pattern.

2. Skeletal Quartz

Skeletal quartz (also called window or Fenster quartz) crystallizes in unstable conditions with more saturation than normal. This causes the edges to grow faster than the crystal faces so the edges stick out and the faces are set back like glass in a window frame giving it a layered or ribbed look. (Hence the name skeletal quartz.) There also may be etchings and cavities with clay minerals, gases or water trapped inside.

3. Phantoms

Quartz crystals developing within mineral solutions sometimes stop growing and then grow again later. In between, other minerals may get deposited on a crystal face. These leave spooky zones of different colors within the quartz, including blood red which comes from the iron mineral hematite. Crystals-within-a-crystal are referred to as inclusions or “phantoms.”

4. Faden Quartz

Faden means “thread” and in the case of Faden quartz, the name comes from the ghostly white line running through it. Faden quartz consists of a series of interconnected flat crystals. The white line is made from cracking during quick crystal growth and fluid trapped in the crack.

5. Twins

Twinning is common and comes in many varieties with quartz, including Dauphine law, Brazil law and Japan law. Japan law twins are a collector favorite. They were named after specimens from a classic locality in Kai, Japan.

6. “The Chiseler”

Rather than an even pyramid shape, chisel quartz has flattened crystals with a wide beveled (slanted and angled) face that looks like a chisel.

7. Spirit Quartz

Spirit quartz, also known as cactus quartz, consists of a primary crystal with prism faces covered by a druse of small second-generation crystals, much like the trunk of a cactus is covered by spines. It is said to be able to connect you with the “spirit realm.”

Collect Different Types of Quartz

Don’t fear skeletons and phantoms. Collect them! The weirder, the better! Each tells a story of growth and misgrowth within the quartz crystal family.

This story about spooky types of quartz crystals appeared in Rock & Gem magazine. Click here to subscribe. Story and photos by Jim Brace-Thompson.

The post 7 Spooky Types of Quartz first appeared on Rock & Gem Magazine.

Many of us have some level of barely started or otherwise unfinished projects stashed away in our studio or shop waiting for the idea or motivation to work on them. Usually, I make my cabs somewhat larger for displaying at shows. I don’t often make my cabs for jewelry use, but this month’s jewelry theme gave me an excuse to resurrect a long-buried, but not forgotten project. 

After struggling to remember what I did with a particular pair of preforms five years ago, I found them together surprisingly quickly. The intended design was to have one piece nested into the larger one. The larger one is a slab of Brazilian agate with contrasting color bands. The smaller piece is a small cab of Laguna agate.

Making the Cabochon

I started with shaping the Brazilian agate slab into a semi-circle with an inverted curve in the bottom to accommodate the smaller cab. I also sketched a design at the top so I could carve a tab that I could drill through for stringing the piece on as a necklace. I shaped the Laguna agate into a pointed teardrop shape sized to fit into the bottom of the larger cab.

I shaped the curve in the larger piece with a silicon carbide Mizzy wheel. The Brazilian agate piece was ready for carving the ridges across the face. I started carving the ridges in the face of the Brazilian agate with a small diamond wheel. I followed this by enlarging and shaping the grooves with a shaped Mizzy wheel. The next step involved sanding the groves with a shaped 220-grit silicon carbide sanding block. The final sanding was done with various shapes of wood bits and a slurry of 220-grit tumbling media. The polishing was done with shaped wood bits and a slurry of cerium oxide.

I drilled the inside curve on the bottom of the Brazilian agate and the top of the Laguna agate cab with a 1mm diamond core drill so I could install a silver wire loop in each of the holes.  I used Epoxy 330 to glue the wire loops into the stones. I assembled the stone pieces by connecting the silver loops. I’m pleased with how the project turned out. 

Steps by Photo

This story about cabochons for jewelry making previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Rush.

The post Cabochons for Jewelry Making first appeared on Rock & Gem Magazine.

Tourmaline Colors

One reason for tourmaline’s popularity is its wide array of colors – over 100! The mineral colors are caused by traces of different chemicals. For example, iron produces blue (indicolite) and green colors and manganese produces pink and red colors. Sometimes tourmaline colors are enhanced by heat treatment.

There are five major tourmaline species.

1. Dravite

2. Elbaite – Named after Elba, Italy. Most gem varieties occur in this species.

• Rubellite – Pink
• Paraíba (named after Paraíba, Brazil)
• Watermelon Tourmaline – (red center and green rind)

3. Liddicoatite

4. Schorl – Black (colored by iron)

5. Uvite

Tourmaline may form beautiful, elongated crystal clusters that are highly sought after by collectors. It is one of the most prized minerals and stunning specimens can be among the most aesthetic examples in the mineral kingdom.

Tourmaline Facts

Tourmaline has a Mohs hardness of 7.5 and crystallizes in the trigonal system. Most crystals are striated, elongated and prismatic. Vitreous luster and conchoidal fracture are also characteristic. Chatoyancy (cat’s eye effect) is found in some tourmalines.

Besides its use in jewelry, tourmaline becomes electrically charged when it’s heated. Piezoelectric properties can make tourmaline useful in the manufacture of various industrial gauges.

Confident Tourmaline

In the metaphysical realm, tourmaline is thought to give confidence, relieve nervousness, promote self-assurance, increase physical energy, enhance the immune system, help negate negative thoughts and relieve tension.

Tourmaline is the gemstone for the eighth anniversary and a birthstone for October.

Where to Find

Afghanistan; Australia; Brazil; China; Congo; India; Italy; Kenya; Madagascar; Mexico; Morocco; Mozambique; Myanmar; Namibia; Nepal; Nigeria; Pakistan; Russia; South Africa; Sri Lanka; Sweden; Tanzania; Thailand; United States of America; Urals; Zambia

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

The post Tourmaline: Properties and ID first appeared on Rock & Gem Magazine.

Colorado train rides for rockhounds are scenic and provide an informative and enjoyable day’s outing. Most of Colorado’s tourist trains today were originally constructed in the late 1800s to serve Colorado mining operations so they give rockhounds a glimpse that few get. If you are a weekend rockhound, a professional geologist or something in between, a few of these excursions need to move up on your must-travel list.

Cumbres & Toltec Geology Train

The Cumbres & Toltec Railroad offers Geology Trains twice a year in June and September. Participants pay for whatever class of car they choose as their permanent seat, but they are free to roam to the outdoor platform cars as they wish. Everyone joining this excursion receives a geology booklet prepared especially for the trip. Another special feature of this excursion includes several guest geologists who roam the train to provide commentary and answer questions.

Be sure to bring your camera and collection bag because this train stops several times along the route to point out geological features and even lets the passengers disembark to walk through the Toltec Tunnel, collect specimens and watch this gorgeous train emerge on the other side.

This train ride is a geological treat. The Cumbres & Toltec travels between Antonito, Colorado and Chama, New Mexico. Grab your list of state dinosaurs as this train ride travels through geologic time from the Precambrian to the Ice Age. You will see alluvial fans, dormant volcanoes, ash flow tufts, as well as the dramatic spires and pedestal conglomerates as you round Phantom Curve. There is metamorphic and igneous rock at the Toltec Tunnel and Gorge.

An included lunch is served at Osier. As you continue to Chama, you travel over the amazing Cascade Creek Trestle as it cuts through volcanic breccia. You will also cross the highest railroad pass in the United States, Cumbres Pass, at 10,015 feet.

Once in Chama, a bus waits to drive you back to the Antonito station. It’s a long, but worthwhile day.

Be sure to get your name on the email list for the 2024 departures. Dates and prices are usually released in early January each year. www.cumbrestoltec.com/events/geologytrain

Durango & Silverton

This all-day round trip starts in the morning from the quaint train station in Durango. In peak season, you may even hear someone playing banjo on the boarding platform. As you depart Durango, the landscape is rather flat, around 6,500 feet in altitude. It takes about three-and-a-half hours for the train to travel 45 miles and climb to the town of Silverton at just over 9,300 feet.

In this writer’s opinion, this train ride probably has the most spectacular scenery you’ll see in all of Colorado. Shortly after you leave Durango, the train starts to climb into forested areas with some beautiful large homes and a lake. Once you pass Rockwood, keep your eyes open on the right side of the train. The sheer cliff called the ‘Highline’, should be called the ‘highlight.’

Unfortunately, there usually are no official geologists on board for this trip. A geology aid available at the Durango station gift shop may be just what you need for your self-guided geology lesson on your way to Silverton. This folded nine-inch geology guide and topographic map opens to 27 x 36 inches and is produced by the railroad and the Fort Lewis College Department of Geosciences.

As the train follows the Animas River and gets closer to Silverton, you may even spot a mine tunnel or two, however, tree growth can make this hard to see.

The train has a two-hour layover in the old mining town of Silverton before you reboard to return to Durango. While in town, you may want to grab some lunch and maybe visit the Mining Heritage Center and Jail adjacent to the Town Hall.

If you return for a longer stay, you can visit the Old Hundred Gold Mine, Mayflower Gold Mill, Animas Forks Ghost Town, or maybe even do a little rockhounding and gold panning. www.durangotrain.com

Royal Gorge Scenic Train

Unlike the first two trains, the Royal Gorge train is a standard gauge track railroad. As passenger train travel decreased, the line was used for freight only before closing in 1983. It was revived as a tourist train by the current owners in May 1999.

The train follows a spectacular, deep canyon carved by the Arkansas River, west from Canon City under the amazing Royal Gorge suspension bridge and for a few more miles before it turns around and returns to Canon City. The entire journey lasts about two to three hours.

Contrary to the train’s marketing strategy, which promotes a breakfast, lunch or dinner excursion, booking a simple coach seat with access to the nearest open car would be my recommendation for the geologist wishing to both see and photograph the gorge. www.royalgorgeroute.com

More Trains

Colorado has so many wonderful scenic railways that it would be impossible to give details on each one. Here are a few more to add to your list.

Georgetown Loop Train: This train has two stations, Georgetown or Silver Plume, but wherever you start, it’s a round trip. The choice of adding one of two tours through the Lebanon Mine and tunnel located along the train’s route is available to guests five years of age or older for an additional charge. Children must be at least 8 years old for the longer mine tour.

Leadville, Colorado & Southern Railway: A two-and-a-half hour roundtrip adventure leaves from Leadville, the highest incorporated city in North America, and climbs about 1,000 feet to the Continental Divide. On board, you will hear stories of the area’s rich mining history.

Cripple Creek & Victor Narrow Gauge Railway: This 45-minute trip is on a two-foot narrow gauge track through the historical mining district of Cripple Creek. No advance tickets are required for this train. These days, the train no longer goes all the way to the town of Victor because of the active gold mining of Newmont Mining. Although this train is more touristy than some of the other excursions, you can see both historical and modern mining at work.

While in the area, plan to explore the town of Victor. You may also want to tour the Molly Kathleen Mine outside of Cripple Creek where you are lowered into the mine in an open metal cage.

Pikes Peak Cog Railway: Visitors have been going to the top of Pikes Peak by train since 1891. After several renovations, the now state-of-the-art cog railroad reopened in May 2021 to take passengers to an elevation of just over 14,000 feet. While at the top, be sure to check out the new visitor center and enjoy a cup of coffee with one of those world-famous high-altitude donuts.

Amtrak Colorado Adventures: If you are looking to make your train trip a longer adventure, you may want to take one of Amtrak’s three or five-day packages leaving from Denver to Glenwood Springs on the California Zephyr.

Boost Your Geology Train

Doris B. Osterwald was a geologist and train enthusiast and she wrote several ‘mile-by-mile’ books on the geology, history and natural features of Colorado’s famous tourist trains. These books make great follow-as-you-go guides. She has passed on her enthusiasm to four more generations of Osterwalds who now operate Western Guideways, Ltd., a great resource for information.

A few of Doris’ books include Cinders & Smoke, Durango & Silverton Railroad; Ticket to Toltec, Cumbres & Toltec Railroad; Rails Thru the Gorge, Royal Gorge Railroad and Highline to Leadville, Leadville, Colorado & Southern Railroad.

The Final Whistle

During the busy tourist season, many of these trains book up early so reservations are recommended. Once you’ve wet your train-riding whistle with some research and advance tickets, just listen…you can almost hear the conductor holler, “All Aboard!”

This story about Colorado train rides for rockhounds previously appeared in Rock & Gem magazine. Click here to subscribe. Story and photos by Sue Eyre.

The post Colorado Train Rides for Rockhounds first appeared on Rock & Gem Magazine.