How to Store a Rock Collection for Documentation

Know what you’ve got and document it! If self-collected, record the locality and date of collection. If purchased, record when, where, from whom, and the price paid. If trading with a fellow collector, record the transaction. “Provenance” is important in the collecting world and adds value. Keep a ledger and include a catalog number on each specimen. On a personal note, as a member of a gem club, I receive collections for our club museum and it is a rare joy when donations come with numbered specimens and a catalog. You can build a catalog with a handwritten ledger or, better, with database software. Whatever route you choose, don’t just keep loose cards with specimens. I knew a lady who lived in a rambling Victorian house and kept a Victorian-style collection—a bit of everything haphazardly placed in an eclectically cluttered funhouse. Regrettably, she stored all info on loose cards and in her head. Over the years, maids vacuumed up the cards while her memory of the specimens disappeared. This left her heirs with a superb collection much diminished in value. If you have specimens you purchased, keep the cards that came with them but also maintain an updated rock collection catalog.

Assessing Your Collection

After documenting your collection, consider having it appraised. Most collections are “specimen collections” of primarily common pieces. While a fossil may be near and dear, if it’s not truly world-class, it’s not worth your time to appraise. Pare down and focus on stuff that is truly rare, unusual, or would be in demand in a market environment. Per the late-great comedian George Carlin, junk is stuff we toss, but stuff is junk we keep. Assess good stuff, not junk!

Where to Get an Appraisal

Where to get a rock collection appraisal? Many gem clubs get requests but are not qualified and as nonprofits are not allowed to provide legal appraisals. Fancy auction houses like Sotheby’s mean paying fancy fees. A good place to start is a local jewelry store with staff who are GIA (Gemological Institute of America) certified. While it’s easy to find someone to appraise jewelry or cut gemstones, it’s more difficult with specimen minerals or fossils. Gem show dealers might appraise what you’ve self-collected or purchased.

However, some warn against going to dealers because they may have an interest in purchasing your collection and provide a low-ball assessment then pressure you to sell to them. It’s best to go to a neutral third party. If turning to an outside entity, seek agencies with qualifications and those versed in the category best matching your collection. Such companies sometimes advertise in hobby magazines or on websites.

Although some auction houses sponsor “appraisal days” with free verbal assessments, most appraisals come with fees based on the assessed value. Appraisers may charge a “per-piece” fee, an hourly fee, or another rate for services. If turning to an appraiser with an especially large collection, negotiate regarding fees and what sort of documentation will be produced.

Appraisal Alternative

Alternatively, do a self-assessment. If a specimen was purchased, what did you pay for it? Keep in mind: what you paid doesn’t necessarily reflect worth. One person paid $9,000 for a sapphire only to discover it was worth $30 after a professional appraisal. That said, compare specimens in your collection against going rates via online shops like Amazon, eBay, and Etsy. Search the internet and gem show aisles to see retail for “like” items.

The main thing to seek? A fair-market value you can document. Don’t go to a “We Buy Gold!” shop offering a commodity price for your carefully crafted collection of gold nuggets. What is the price fellow collectors might pay? Whatever route you choose, have a rationale behind assigned values. Use hard market data either deduced by yourself or obtained from an impartial third party, not based on sentimental value. Also, some insurance companies don’t accept self-assessments and insist on independent evaluations. This could cost you big bucks, so focus on unique pieces within your collection. Search the web for appraisers within your region.

Where to Get Insurance

After appraising a rock collection, most turn to their regular homeowner’s insurance. This can be the most inexpensive option, but while many companies are versed in insuring jewelry, not all have expertise regarding specimen minerals and fossils. And while homeowner’s insurance may provide coverage in a “personal articles floater,” such a floater may be exorbitantly expensive and most fail to offer full replacement cost. Seek better deals with specialized insurers offering “collectibles insurance.” As an example, one collector spends $120/year with a specialized insurer for a 200-piece collection worth $17,000 when her regular homeowner’s policy turned her down.

What Insurance to Get for Your Collection

You can get a rider on your homeowner’s insurance policy, but they say not to bother for individual pieces or an entire rock collection that isn’t worth at least a minimum amount. Most policies exclude or severely limit the value of coverage for collectibles, but if you have a small collection of ordinary specimens, this may be your best bet.

Alternatively, some companies focus specifically on gems and collectibles both for appraisal services and insurance for especially high-value collections. When seeking insurers—as in seeking appraisers— check advertisements within hobby magazines and/or do an internet search.

Whatever route, seek a policy insuring against theft, accidental breakage, fire/ water damage, and natural disasters. If you attend gem shows as an exhibitor, consider coverage for travel and show attendance. Finally, seek insurers versed in the unique properties involved in one-of-a-kind collectibles, including such concepts as “replacement value” versus “fair market value” or “agreed-value coverage” versus “actual or standard cash value.”

Protecting Your Rock Collection

If you wish to insure a collection, you’ll need to provide evidence that you’re protecting that collection. Store specimens in cabinets or flats. High-value items should be locked in a safe. Place small items with outsized values in a safety deposit box. Alternatively, adopt a high-strung Doberman Pinscher! As some members of my Ventura Gem & Mineral Society learned during the devastating 2017 Thomas Fire in California, even rocks burn. Have smoke detectors in every room of your home and keep them charged with fresh batteries to protect both your rocks and yourself.

Those with more means might install a sprinkler system. This is a step above, but it’s worth it when you consider what happened to the national museum in Brazil, which lacked smoke detectors and sprinkler systems and suffered a total loss of national treasure. Some choose to keep a secure location within their homes for especially valuable pieces, which can go as far as a “safe room” with a locked door and inside closets and vaults. Do your best to protect the best of what you’ve got!

Transitioning Your Rock Collection

If you’ve devoted time to documenting, appraising, and insuring your collection, you certainly want to consider what happens after you‘ve departed the scene. Do you care if your collection is broken up, or do you hope it might be kept whole? The latter is problematic unless you have an heir who shares your passion or unless you provide an endowment to a museum to pay for storage, display, and upkeep. First, consider immediate heirs. Desires should be spelled out in a will or, better, a trust. But if heirs have no interest, consider liquidating the collection in your lifespan.

If you do wish to keep it intact, build contacts with a local museum and make your wishes known. Museums want collections with clear provenance and no issues (e.g., no specimens collected from national parks or countries with human rights abuses in gemstone districts). Most cannot guarantee specimens will be put on display and can’t guarantee they won’t be decommissioned and disposed of. If you truly want your collection to have a permanent place in a museum, you may need to accompany it with a healthy cash endowment.

Continuing the Conversation…

This topic is not typically discussed within gem societies but, in my humble opinion, how to store a rock collection properly should be discussed. Our collections are a reflection of ourselves. How might we best preserve the best of ourselves for future generations?

This story about how to store a rock collection properly previously appeared in Rock & Gem magazine. Click here to subscribe. Story and photos by Jim Brace-Thompson.

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Many of us have often wondered if geology careers were possible. Geology is so interesting… but could it be a career? Here are eight geology careers that can provide a good living and fulfilling work.

1. Museums

Museum jobs are increasing by an amazing 12 percent each year as projected over the years 2021-2031 by the U.S. Bureau of Labor Statistics. Most require a master’s degree and the median annual salary for a curator was $50,100 according to May 2021 data. Johns Hopkins University offers degrees in museum studies.

2. Environmental Geology Careers

Environmental geology careers are growing in prevalence in many countries. Have you ever driven past a service station where a tank was being pulled out of the ground and the tank and surrounding soils were being tested and removed/replaced as needed? Did you know a geologist put together the plan for testing the soil and groundwater and determining the best strategies for remediation? The environmental geologist career is high-paying, sometimes six figures per year.

3. Geomorphologist

Geomorphologists are in demand in government and private companies. Their work focuses on understanding how landforms change over time. They perform hydraulic, hydrologic and geomorphic analyses to map resources such as groundwater and petroleum. If you love math and geology, geomorphology could be a perfect match. The career pays well too!

4. Hydrographic Surveyors

Hydrographic surveyors use instrumentation to map out the shape, contours and depth of streams, lakes, inlets and ocean bottoms. They often work for government agencies or private companies doing surveys for the government and nonprofits. For example, ecological restoration of channelized streams requires a hydrographic surveyor to determine the best approach to restoration. The median salary is around $80,000 per year.

5. Gemologist

When we buy a diamond or any precious colored stone from a fine jeweler, a gemologist was responsible for identifying, grading and selecting it. Careers include working as a lapidarist, bench jeweler, consignment director, appraiser, jewelry litigation expert witness, a fine jewelry polisher, and a precious metal tester. A college degree in geology is not necessary to get started gem cutting. There are many gemology schools with programs and diplomas.

6. Mineralogist

Mineralogists collect core logs, conduct geochemical and geophysical surveying, create geological mapping, and examine geochemical samples like petroleum, minerals or rocks using such instruments as gas chromatographs, carbon analyzers, microscopes and spectrometers. They perform original scientific research to determine the ages and other characteristics of specific soils, minerals and rocks. They oversee processes that separate minerals from their ores. The educational requirement for most mineralogist jobs is usually a master’s degree at minimum.

7. Mud Logger

Mud loggers analyze drilling fluids after they have been drilled up. They analyze the fluids in a laboratory. Mud loggers determine the position of hydrocarbons to depth. They also monitor natural gas and identify the physical characteristics of outcrops available in a given area of study.

8. Wellsite Geologist

Wellsite geologists are the next level up from mud loggers and you must be a mud logger first. Both require a bachelor’s degree in geology. Wellsite geologists classify rock cuttings removed from wells. They use rock-cutting data, core samples and specialized tests to advise gas and oil operators on how deep to drill wells. They prepare reports during and after the drilling. This is one of the highest-paying geology jobs with salaries topping six figures per year.

Geology Careers Provide Varied Work

The pay can be good. But geology careers are not just about making money. It’s also the wide variety of work and the demand for it. The Bureau of Labor Statistics projects a 4.5 percent job growth in the geosciences, including environmental geoscientists, from 2021 to 2033, a 5 percent job growth in geoscientists, not including hydrologists, overall, and a 5.4 percent job growth increase in geoscience technicians.

Consulting Geology Careers

Dennis Papa, P.E. is a principal at dpSTU-DIO LLC, Environmental Consulting and Design with offices in Richmond, Virginia and Providence, Rhode Island.

“Back in the late 1980s (seems like the Precambrian!) many undergraduate geology programs were focused on petroleum exploration and mineral resources. That is what I was originally interested in, imagining a career looking for oil-bearing formations. When jobs in petroleum and coal exploration started to become scarce, the environmental industry was just ramping up. I was drawn to the idea of a job that offered a mix of both fieldwork (doing well installation, groundwater and soil sampling) as well as office work to write reports, use software, and engage with other experts and clients to study a contamination problem.”

Many wonder if a professional geologist license is needed. “The P.G. is simply a test that each state offers to a geologist who has the requisite degree and minimum years working in the industry. A national exam is now offered to standardize the test. but not all states require it. Many states require a P.G., or working directly under a P.G., to practice geology, but it is not a requirement for all careers in geology and is certainly not required once starting out.”

Geology Tools & More…

As with any job, sometimes the fun is in the tools used. “Tools always offer that tangible connection to your trade. The geologist hammer is indispensable. A hand lens magnifier, soil color chart, and grain size chart used to compare sorting, size, etc. of sediment and rock samples are important tools to help provide useful data in standardized terms. Aerial photographs are used. We also routinely use a water level meter to accurately measure depth to water level.”

Dennis works closely with other specialists. “We rely very heavily on experienced and licensed well drillers, geotechnical engineers, wetland scientists, soil scientists, archeologists and geophysicists.”

In Dennis’ opinion, “I am partial to the environmental consulting field because it has offered me so much. However, I think there are so many geology career paths to choose from, and there have been so many advances in the subspecialties, that it just depends on your particular interests. Some offer more time in the field, others more opportunity to work in an office or laboratory. And if you can’t decide, the beauty is that many geology jobs offer a combination of both.”

Geologist

Claire Starke is a geologist with a large consulting firm with offices around the world.“I knew I wanted to be a geologist at age seven and I chose environmental geology because I felt that it would get me further in the business world and encompass different types of jobs. I graduated in the spring of 2021 so I was going to school through a time when environmental remediation and sustainability was a large chapter covered in all my major classes.”

A typical field day for Claire includes, “I mainly work with environmental sampling in groundwater monitoring wells. I use different types of well pumps to pull the water out of the well at a low flow rate. We work with drilling companies, and they will do the physical placement, but a geologist will tell them where to put the well, how deep to drill, and how deep to place the screen of the well. I have worked with hydrologists and hydrogeologists to figure out groundwater flow. I have worked with chemists to discuss the chemicals found in groundwater samples.”

What geology fields are best? “In my opinion, environmental remediation is the best geology field for the time we are in now. There are always new chemicals being found to be dangerous to human health, someone is needed to address the issue and needed for remediation, so it’s a sustainable career because the job is never done. You get a very nice blend of field and office activities. You also get to make the world cleaner and healthier in small and big ways.”

This story about geology careers appeared in Rock & Gem magazine. Click here to subscribe. Story by Deborah Painter.

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Old Rock Day – January 7

This day is set aside (though no one knows how long it has been observed or when it was first celebrated), to consider how old the Earth is and how it has shaped our lives. It’s also a shout-out to some of the earliest geologists like the Theophrathes, Pliny the Elder, Ulisse Aldovandi, James Hutton and William Smith.

National Jewel Day – March 13

This special day is set aside to appreciate precious stones and jewelry. From the earliest examples of stone, bone, and shell jewelry, to the most lavish and intricate designs of today, National Jewel Day is meant to recognize them all. Those who choose to participate are encouraged to wear their most spectacular bejeweled pieces and take the occasion to gift jewelry to those important people in their life.

Geologists Day – April 7

This day is dedicated to those folks who make it their life’s work to explore, research and disseminate their knowledge of rocks and Earth’s history. It is also the time to appreciate all of those things in our lives that we have or know because of geologists. This includes such daily used items as toothpaste and even cell phones. Younger folks contemplating a career in geology can take this opportunity to discuss with practitioners in the field, what the job is actually like.

Earth Day – April 22

You can’t get any “Earthier” than rocks, gems and minerals. This is a day for rockhounds to explore and to appreciate Earth’s treasures.

Nickel Day – May 16

Devoted to the mined element, nickel, this day was created to acknowledge this important metal. Nickel has been used by humans for at least 2,000 years. By the middle of the 19th century, it was ubiquitous in American coinage as well as that of other European nations.

Dinosaur Days – May 15 & June 1

Dinosaurs lived millions of years ago, but they’re top of mind today. So much is still unknown about these fascinating creatures. Celebrate what we know and anticipate what we don’t on this fun day for young and old alike.

National Caves & Karst Day – June 6

This day is dedicated to the majesty and importance of these amazing rock formations. Most people know what caves are, but few are familiar with “karst” landscapes. A karst landscape is characterized by rocky hills, aquifers, springs, sinkholes and caves. Hundreds of different minerals and gems are found in caves, and 40 percent of drinking water in the U.S. comes from karst aquifers.

World Oceans Day – June 8

Beach finds from shells to rocks, minerals and sea glass are a favorite. Celebrate the oceans that bring us this bounty.

International Drop a Rock Day – July 3

This a day for having a bit of fun while inspiring kindness toward others. Across the world, individuals, families, and groups of all types get creative and paint rocks with pictures, themed messages, or even advertising and hide them. Anyone can try to find them. When they are found, the lucky holder of that rock can keep it, hide it again, or if it is part of a local promotion, contact the sponsoring group. This highly popular activity is not restricted to International Drop a Rock Day; many groups do this throughout the year and hold rock-painting parties before going out and hiding them.

International Rock Day – July 13

Sometimes referred to as World Rock Day, this day is intended to celebrate and to contemplate the importance of rocks to humankind. It is to honor the rock as one of the most fundamental aspects of human survival. If there is one day per year to give rocks their due, this is it!

National Pet Rock Day – September 1

This tongue-in-cheek holiday is dedicated to the 1975 marketing scheme that led to the sale of over one million pet rocks. On this day, many people “adopt” a pet rock at functions planned to celebrate this phenomenon.

Collect Rocks Day – September 16

Held since 2015, Collect Rocks Day celebrates all of the diverse types of rocks and all of the different places they can be collected, no matter where in the world you live. It is a celebration of Earth and geology for everyone.

National Fossil Day – October 16

As the name implies, this day is reserved for appreciating and exploring fossils. Of the approximately 250,000 different fossilized species that have been identified, it is estimated there are millions more to be found. Many groups organize fossil hunts and expeditions on this day in early fall. Be sure to find one near you.

This story about rockhound holidays appeared in Rock & Gem magazine. Click here to subscribe. Original story by Chris Bond. Updated yearly to reflect current dates and holidays. 

The post 2024 Rockhound Holidays first appeared on Rock & Gem Magazine.

While viewing the front of the Brazilian agate slab, I spotted a much more interesting group of features that I could use to enhance the overall aesthetic of the piece. A three-inch circle would allow me to bring out all of the best patterns that the piece could offer. I sketched the circle and added a curved feature on the top so I could drill a hole for suspending the piece as a pendant.

Where do I get my project inspiration? First, this column pushes me out of my usual cab shape routine and into using different materials, shapes, textures, patterns or colors. I read a lot of books on lapidary and jewelry design and also subscribe to a couple of magazines that have current jewelry styles and materials such as blue gems and minerals. Sorting through my multiple boxes of slabs often triggers my imagination too.

MAKING THE SHAPE

Before and during grinding, I make sure to follow proper lapidary safety precautions. While grinding the piece to a preformed shape, I used a one-inch diameter Mizzy silicon carbide wheel run dry to shape the inside curves on the top section. I drew a line halfway up the girdle as a guide for shaping the dome of the cab. I used an ultra-fine Sharpie felt tip pen to draw the line.

After I finished shaping and sanding the front of the Brazilian agate cab, I turned it over and focused on the translucent area. It was to be enhanced and ultimately be the main focus of the cab. From the start, I intended to drill four holes in the back of the cab so they would show through from the front. I drew a curved line in the center of the translucent area so I could lay out the position of the four holes. (It gives more visual interest if the holes aren’t in a straight line and if they are varied in size from larger to smaller.) I also made sure that they were evenly spaced between the holes.

DRILLING & FINISHING

I drilled small pilot holes for each bit and placed the bits in these holes to verify the correct spacing. I started drilling with a small coarse diamond bit. To get the best drilling action on the bits, I turned them on their sides. If you try drilling by placing the bit vertically, the very center of the bit does no work because it is spinning in one spot. By placing it sideways, the diamonds in the bit sweep across the cab and remove material.

I gradually stepped up in bit size and grit size until I reached the desired hole size. Because I wanted to ensure that the holes were highly visible from the front I drilled the holes up to 1mm from the front of the cab. I used an inside caliper to measure the 1mm depth. The final grinding step involved using a very large bit to chamfer the top edge of the hole to remove any chips.

The finishing steps were done with shaped wood bits using 220 and 400-grit tumbling media followed by shaped wood bits and cerium oxide polish.

The finished Brazilian agate piece came out much better than I had expected!

This story about Brazilian agate appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Rush.

Step By Step

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WHAT’S IN A NAME?

Rock? Food? What’s up with the foodie name? Marketing! It’s kind of like a famous line from the classic movie, Spaceballs. “Merchandising, merchandising, where the real money from the movie is made.”

Grape agate is a fun marketing name for a fascinating mineral – botryoidal purple chalcedony. Plus, grape agate is easy to say, remember and visualize.

DEFINITIONS

Botryoidal – In Ancient Greek, this term literally means “bunch of grapes.” It refers to a mineral habit that is made of rounded segments. This habit is found in other minerals such as hematite, malachite, chalcedony, goethite, fluorite and smithsonite.

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. Chalcedony’s name is said to come from the Greek port of Chalcedon.

AGATE IDENTIFICATION FACTS

Grape agate appears as small, round nodules around two to eight millimeters across. Its colors can vary, ranging from translucent to a deep purple or lavender hue. It can also be white, gray, blue or green. (Maybe unripe grapes or the green kind from the store?) These vibrant colors are caused by traces of minerals, such as manganese and iron, that were present during the formation process.

One interesting feature of grape agate is its texture. The individual crystals that make up the grape-like clusters are usually small and spherical. They can have a bumpy or drusy surface, giving them a rough yet sparkling appearance.

When examining grape agate, you may notice tiny hollows or vugs on the surface. These are remnants of gas bubbles that were present when the crystals formed.

A NEW & RARE MINERAL

This is a newcomer appearing on the “rock” scene around 2016. Grape agate is found in only a few places on Earth — Indonesia and west of the Green River in Utah. It is a popular mineral for use as a display piece or in jewelry.

BEWARE OF MINERAL DUPES

Real grape agate is highly sought after and can be pricey depending on quality, especially the color and size. The deeper and bolder the color, the higher the price. And the bigger, the better. Beware though, some grape agate is dyed to achieve a more desirable color.

CARING FOR GRAPE AGATE

Grape agate has a Mohs hardness of around 6.5 to 7. With individual “grapes” sticking out, they can get jostled and come loose or fall off completely. Handle it with care and avoid contact with rough surfaces. When left in the sun, grape agate can lose its color so avoid setting it in a sunny spot.

This Rock & Gem Kids story previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Pam Freeman.

The post Grape Agate: A Food Look-Alike Mineral first appeared on Rock & Gem Magazine.

Agate Facts

Agate has a seven Mohs hardness, making it desirable in the lapidary trade. Agate is translucent and exhibits a vitreous luster. As with other varieties of quartz, its chemical formula is SiO2. The name agate comes from the river Achates in Sicily and was given that name by the Greek philosopher, Theophrastus. Agate names can be derived from the location where they are found such as Botswana agate or Laguna agate or because of a feature they exhibit like lace, fire or moss.

How Agates Are Formed

Agate formation takes place when silica solutions fill voids in cavities layer by layer such as in Florida’s agatized coral. The voids typically are in solidified volcanic lava flows and the layering over long periods of time can result in different colors because of chemical changes in the silica solutions. The layering can deposit the chalcedony in concentric circles around the wall of the cavity or build the layers up from the bottom of the cavity.

Decorative Agates

Agate is used to produce cabochons, beads, and free-form objects in jewelry making. Book-ends, ashtrays, and sculptures are also made using agate.

Positively Agate

In the metaphysical realm, agate is said to change negative energy into positive energy and to heal anxiety and internal anger. Agate may also help with concentration and boost mental function.

Where to Find Agates

In the United States, agates are found in Oregon, Wyoming, Montana, Arizona, Idaho, California, Washington, New Mexico, Iowa, Wisconsin, Michigan, Minnesota, Utah, Florida, Colorado, Arkansas, and Nevada. Around the world, they are found in Australia, Germany, Brazil, Czechia, Botswana, Mexico, Morocco, Afghanistan, Argentina, Canada, Chile, India, China, and over 40 other countries.

This agate field guide appeared in Rock & Gem magazine. Click here to subscribe. Story by Richard Gross.

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Throughout history, the precious metals gold and silver have been admired for their beauty, hoarded for their value, coveted for their workability, fashioned into jewelry, and coined as currency. But the story of platinum metal is much different. It was once cursed, discarded as worthless and used as a counterfeiting agent.

Platinum Metal

Platinum is a rare, silvery-white metal. Its specific gravity of 21.45 and Mohs hardness of 4.0 make it somewhat more dense and much harder than gold. Although not as quite as inert as gold, it nevertheless does not oxidize, retaining its gleaming, white metallic luster and taking a superb polish. Platinum also has excellent electrical conductivity, corrosion resistance, and catalytic properties, plus a high melting point. Platinum is about as rare as gold but, unlike gold, it is rarely found in economic concentrations suitable for mining. Platinum occurs in some 20 minerals and is also found in nature, usually as silvery-gray grains and nuggets.

Platina

In the early 1500s, Spain’s colonial gold miners, in what is now Colombia, found platinum in gold placers. They roundly cursed this discovery because the metal then had neither use nor value and was difficult to separate from gold. The Spanish named the metal platina, a derogatory term meaning “little silver” and the root of our English word “platinum.” In the early 1600s, Spanish mint workers at the future site of Bogotá, Colombia, dumped large amounts of worthless platina into rivers to create extraordinarily rich placer deposits that would end up being mined centuries later. In 1670, Spanish metallurgists found platina’s first practical use as an alloying agent to enhance the hardness and durability of bronze cannon.

In 1700, metallurgists learned that gold alloyed with platina changed very little in weight or color. Spanish mint workers subsequently began adulterating gold coins with platina and pocketing the displaced gold. To suppress this rampant counterfeiting, the Spanish Crown banned private possession of platina under penalty of death. But when counterfeiting continued, it began offering a bounty for all platina turned in, giving the metal its first formal valuation. The Crown later secretly debased its own gold coinage with platina, using these “special” issues to settle foreign debts.

The Russian Experience

In 1824, Russian gold prospectors in the Ural Mountains discovered the rich Nizhne-Tagilsk platinum placers. The Russian government quickly monopolized platinum mining and refining, then began fabricating platinum jewelry which consumers promptly rejected as a cheap “silver imitation.” Determined to benefit from its platinum, the Russian government next issued legal-tender, platinum ruble coins. But by 1843, the number of circulating platinum rubles had far exceeded the official mint issues because European counterfeiters had been acquiring worthless Colombian platina and striking counterfeit rubles.

Coming of Age

During the 1850s, European scientists took advantage of platinum’s high melting point and chemical inertness to fabricate high-quality laboratory instruments and crucibles. Growing demand soon drove platinum’s price to $1.50 per troy ounce, higher than that of silver. By the 1890s, platinum’s extraordinary catalytic properties that accelerated many chemical reactions had made it the standard catalyst for acid manufacturing and petroleum “cracking.”

At the same time, platinum gained popularity as a jewelry metal when prestigious designers Louis Cartier, Charles Lewis Tiffany and Peter Carl Fabergé began combining platinum’s brilliant, white gleam with the glitter of diamonds and sapphires. By 1905, combined jewelry and industrial demand had driven platinum’s price above that of gold (then $20.67 per troy ounce) for the first time. Breaking the gold-price “barrier” earned platinum worldwide acceptance as a bona fide precious metal.

Industrial Platinum Metal

Platinum demand soared in the 1970s when federally mandated reductions in automotive-exhaust emissions required new automobiles to be equipped with catalytic converters to break down noxious hydrocarbons and nitrous oxides. Today’s automotive converters contain about one-half a troy ounce of platinum in a ceramic honeycomb called “autocatalyst,” which is currently the biggest use of platinum. Eight million troy ounces of platinum are now mined each year, mostly in South Africa and Russia, with lesser amounts recovered in Canada and the United States. The United States’ production comes almost entirely from Montana’s underground Stillwater Mine.

Jewelry Platinum Metal

About 1.5 million troy ounces of 85-to-95- percent-pure platinum are made into jewelry each year. Platinum purity, expressed in parts per thousand, is stated in hallmarks similar to gold karat marks. A “Pt950” or “Plat950” hallmark indicates a composition of 95 percent platinum; the remaining five percent is usually copper or palladium which enhances workability. Platinum’s white gleam complements or contrasts nicely with both colorless and colored gemstones. Popular composite jewelry creations combine the rich yellow of gold with the gleaming white of platinum—a fitting combination for a metal that, in less than 120 years, has gone from rags to riches.

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

The post Platinum Metal’s Rise to Fame first appeared on Rock & Gem Magazine.

Opal is a well-known example of a mineral whose color is caused by a physical phenomenon called “diffraction.” Other phenomena include iridescence, a rainbow effect seen in iris quartz and pearls; chatoyancy, which we see in cat’s-eye stones and some malachite; asterism, which is displayed in star stones; aventurescence, as seen in aventurine quartz and sunstones; adularescence, seen in moonstone; and play of color, or the alexandrite effect, seen in the alexandrite variety of chrysoberyl and some garnets. In every one of these groups, the cause of the color is related to some internal physical structure and not a metallic impurity or element in the mineral’s structure.

Opal Color

For centuries, people tried to explain the play of color seen in many opals. Finally, in the 1960s, we developed equipment that could actually see the internal structure of opal. It revealed a very orderly arrangement of submicroscopic spherules of silica. These spherules and the spaces between them acted as a diffraction grating, spreading light into its various colors. The sizes of these spherules and the angle the light struck them, coupled with the viewer’s angle, determined which color wavelengths were canceled and which ones were reflected. Diffraction of light results in opal’s play of color.

Labradorite Color

A more common mineral that gets its play of color from diffraction is the feldspar mineral labradorite. This mineral can develop in huge formations, resulting in outcrops that give off flashes of color.

Labradorite crystallizes in thin wafers in parallel layers that repeat to form a diffraction grating. This has the effect of separating light into its colors, giving labradorite a play of color that depends, in part, on the angle of the source of light. The thickness of each crystal and each cluster of crystals in their parallel layers also affect which color is seen. Labradorite can flash bronze, blue, green, and in some cases, red or violet in an overall groundmass of gray to blue. It is thought the gray color of the groundmass is due to the scattering of light by the internal structure.

Play of Color

Another attractive feldspar mineral is adularia. Like labradorite, it develops as thin crystals that line up in parallel arrangement and act as a diffraction grating. But adularia does not show a play of color. The twinned arrangement of the crystals simply scatters light. While it can also be shades of gray, pink, peach, green and brown, it is best known for a bluish-white color that is reminiscent of the moon.

Properly cut adularia gives off a cloudy sheen that seems to float throughout the polished stone. We give this lovely form of adularia the name “moonstone.”

Why does adularia have little color, while labradorite is a riot of color? Minerals color variations are because of minor variations in the refractive index of the labradorite crystals involved. In adularia, the refractive indices of the crystals are virtually the same.

Iridescence

Iridescence is described as a play of changing colors on a surface of a mineral. A prime example is the look of oil spread over the surface of water. The oil particles have a different refractive index than the water, and this physical difference results in a play of color.

The most common example of this phenomenon is called “peacock ore”, which is actually the mineral bornite (copper sulfide). A freshly broken surface of bornite quickly oxidizes, forming a thin oxide mineral layer whose refractive index differs from bornite’s and creates a play of color. More subdued examples of this iridescence are seen on some crystal surfaces of pyrite, cuprite, chalcopyrite and hematite.

Pearl Iridescence

Iridescence is what gives pearls their soft, moonlike luster, called “orient.” Pearls are made up of layer upon layer of microscopic crystals of hexagonal aragonite. The refractive indexes of these layers are the same. Colored and black pearls result from inclusions that get into the pearl’s structure.

Mother of Pearl’s lovely shimmer, or glow, comes from the interior lining of shells, which is made up of two different substances: the calcium carbonate mineral aragonite, which forms microscopic hexagonal crystals, and conchiolin, a fibrous protein that forms in layers in parallel arrangement. The parallel fibers of the conchiolin are the key to creating the iridescence we see in mother of pearl, also called “nacre.”

Chatoyancy

When the fibers of a mineral develop in a parallel arrangement, they impart a silky shimmer or glow of light, called chatoyancy, that can be very appealing. You can expect to see this shimmer in a range of minerals. Asbestos is a very common example. When the asbestos is invaded by silica, it can form what we normally call tiger’s-eye, which is a very useful chatoyant gemstone with a silky luster. The invading silica negates the hazard we normally associate with asbestos.

Iridescence Within Stain Spar

One variety of gypsum, called stain spar, also shows iridescence, or glimmer of light. The mineral looks like silk cloth, whose fibers are also arranged in a tightly woven, parallel structure. Another example of iridescence is seen in some malachite. This copper carbonate usually crystallizes in tightly packed needles, which grow in slightly diverging radiating masses. When freshly broken, these near-parallel fibers give off a shimmering green color.

Asterism is seen in minerals like diopside, gem corundum, some moonstones, and several others. In these species, included fibrous crystals of the mineral rutile, in an intersecting arrangement, reflect light in a six-rayed star pattern. This physical phenomenon is what creates rare star sapphires and rubies, which are very valuable varieties.

Cat’s-eye gems exhibit chatoyancy, as well as a single, bright, linear reflection from tightly packed parallel fibers of a second mineral. Lapidaries give these gemstones a slight to strong dome and orient them so that the included mineral, often rutile or tourmaline, runs straight across the curved surface to form a single bright line, much like the vertical iris in a cat’s eye. It is important to know that these included needle crystals are all oriented along just one of the several growth axes of the hexagonal corundum stone.

Hexagonal Minerals

Hexagonal minerals like ruby and sapphire develop along four axes: one vertical “C” axis, from which three axes develop at right angles to the “C” axis, 60º from each other. For a star gem to form, the included mineral orients along the two arms of each horizontal axis to create a six-rayed star.

Chatoyancy is also seen in the cubic mineral gem garnet. The difference is that garnets form in the cubic system so the “star” forms from needle crystals that have oriented along the two horizontal axes that make up the cube form. Only two axes extend away from the single vertical axis, so the four arms of these axes with their parallel, included needles can orient to form a four-rayed star.

Understanding Aventurescence

Aventurescence is another physical phenomenon that involves inclusions. In this case, the inclusions are usually large enough to be visible and are scattered throughout the crystal mass, rather than oriented in a particular alignment. These scattered inclusions act as reflectors that scatter the light entering the host mineral.

An intriguing example of this is the manmade material called “goldstone”, which is glass with copper inclusions that give the glass a bright reddish-gold color.

Aventurescence is named for a quartz variety called aventurine, which is a lovely green color thanks to included chrome mica. These tiny, green flakes, or spangles, are scattered throughout the quartz, giving it a diffused green color of varying intensity that is very attractive.

The most attractive gem that falls into this category is the feldspar variety sunstone. This very lovely gem is found in several places in Oregon and shows a fine orange to red color due to included copper diffused throughout the gem. In some examples, the copper orients within the feldspar so that wisps and feathers of color are prominent in the gem. Sunstone claims in Oregon are occasionally opened to collectors for a fee.

Alexandrite Effect

Finally, the alexandrite effect is seen in very few minerals whose color is based on the type of light source. The chrysoberyl variety alexandrite is the obvious example.

Alexandrite has a light absorption band that, in sunlight, can split light into two different transmission areas. Under sunlight and fluorescent light, some of the blue wavelengths are absorbed, so green becomes dominant. When seen under in incandescent light, alexandrite is red.

As you collect colorful minerals, be aware that not all of them owe their color to a trace element inclusion. This is another area of interest you can pursue as you enjoy our wonderful hobby.

This story about what gives minerals color appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Jones.

The post What Gives Minerals Color? first appeared on Rock & Gem Magazine.

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.

The rocks that animals consume are called gastroliths which literally translates to “stomach stones.” Gastroliths can be found in a range of animals including birds, reptiles, fish, insects, and even some mammals. Any type of stone can become a gastrolith; it just has to have been swallowed to join that club.

Why Do Animals Eat Rocks – Herbivores

What is an herbivore? It’s an animal that primarily eats plants. (Did you know that rocks and minerals play a role in plant growth?) So why do animals that eat rocks include herbivores? Though animals that eat stones are not all herbivores, those that are, have a special reason to consume rocks. Plant material is made up of cellulose. Cellulose is one of the most abundant, yet hard-to-digest materials found in plant material.

Cellulose is difficult to break down inside the body with only stomach acid. Why do animals eat rocks? Because stones inside an animal’s gizzard help to break this material down further before transferring it to a second stomach for additional digestion. This process smooths the stones over time. Many animals then regurgitate these smooth stones in favor of more jagged ones to help with the breaking down of food.

Why Birds Eat Rocks

Birds are the most common group of animals that eat rocks. These rocks aid in their digestion. Folks who raise birds are familiar with this as many supplement their feathered friends’ diets with grit, which are very small stones with uneven, blunt edges.

Birds don’t have teeth, or stomachs like mammals, instead, have a gizzard which is a muscular mass attached to their version of a stomach. The gizzard is where their food is ground up and mashed with the aid of the stones that they have swallowed.

Most avian consumers of stones are ground-dwelling or flightless birds. Chickens, turkeys, ostriches, and even penguins routinely swallow jagged little rocks while they are out and about foraging for food to help their digestion. Research has found that in ostriches, between one-fifth and one-half of their stomach contents are gastroliths.

These account for about one percent of the bird’s total body mass. It is speculated that the ratios and percentages are similar for other birds too (at least the ones that eat rocks).

There are some flying birds though that have been documented to be stone-eaters.

Crows and parrots are known to eat small rocks to aid their digestion. Some swimming and flying birds like ducks are also known to eat small grit-stones to help them break up their swallowed food. It is very likely that all birds swallow stones in some capacity to help break down their food.

Why Reptiles & Amphibians Eat Rocks

The need for birds to swallow rocks is pretty well understood. The same cannot be said though for reptiles. The prevailing theory for decades was that for swimming reptiles like crocodiles, swallowing rocks helped with their buoyancy. Given that they like to hover just below the water’s surface, this might be a plausible reason. A bellyful of rocks could help weigh themselves down enough so they don’t float all the way up to where they can be easily seen by their prey.

Much recent research about why do animals eat rocks, however, has suggested other hypotheses for this behavior in reptiles. Scientists have found that gastroliths make up less than two percent of the body mass of reptiles. They calculate that for the gastroliths to have the previously believed effect of achieving buoyancy, that number should be more than six percent of the animal’s body mass. The act of breathing, filling, and emptying their lungs with air, has more of an effect on buoyancy than the two percent of their body weight comprised of stones.

Current speculation about why do animals eat rocks is that the swallowed rocks help to stabilize the reptiles’ bodies in the water, reducing the tendency to roll from side to side. Though not reptiles, frogs eat rocks too.

Like birds though, the hypothesis is it helps them break up the insects they eat to get more nutrients from them. Earthworms are another animal that consumes rocks. Their internal digestive muscles, along with teethlike structures known as “grinders” break up plant material so that nutrients can be extracted from them.

Why Do Animals Eat Rocks – Sea Life

A variety of sea life eats rocks. Fish, clams, seals, and even whales are known to eat rocks, though in some cases it is believed to be inadvertent. Like crocodiles, it was once thought that sea lions, seals, walruses, and whales swallowed rocks to make diving easier.

Like other hypotheses that have arisen in recent years, the thinking for these sea creatures is that since many find their food on the ocean floor, they inadvertently scoop up rocks while scooping in on their food. This is seemingly more probable than swallowing rocks to help them dive.

The problem with the rocks as a diving aid hypothesis is that they would have to swallow huge rocks to make a difference. There is no evidence that they seek out and swallow big, heavy rocks.

Several species of bottom-feeding fish are also known to eat rocks, though again, it is not entirely known if this is intentional to aid in digestion, or accidental consumption while grabbing food off the seafloor. Other possibilities have arisen to explain this phenomenon in swimming mammals.

Alleviate Hunger

It is possible that some of these, and possibly other animals that eat rocks, do so to help alleviate hunger. Taking up space in their stomachs could potentially make them feel more full. Another conjecture is that they, like birds with their gizzards, swallow rocks to help their digestion (sans gizzard) and to break down the wide range of items that they may accidentally swallow.

One of the more unusual sea-dwelling rock eaters is a type of clam found in the Philippines, Lithoredo abatanica. The name roughly translates to “rock shipworm from the Abatan River.” Many would not recognize this animal as a clam.

It is fattened, worm-like, translucent, at least four inches (10 cm) long, with a shell complete with shovel-like projections. It is not akin in either appearance or bloodline to the familiar Quahog or Atlantic type of clam, but instead is a member of the shipworm family. These clams eat wood, but the newly discovered Lithoredo abatanica eats limestone, not wood. It burrows into rock and excretes sand. It is not yet known if these creatures actually derive any nutrition from these rocks.

The consumption of gastroliths by animals is a more common practice than most people would realize. Whether it be for digestion (with or without a gizzard), buoyancy, diving, deriving minerals, or feeling full, it is a widely practiced behavior in the wild animal kingdom. The next time you see a small, unassuming, round stone on the ground, it may well have been on quite a journey inside of any number of animals before finding itself at your feet.

This story about why do animals eat rocks previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Chris Bond.

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