I’ll never forget vacationing in Thailand, trying to decide whether to buy a pair of jadeite earrings. The beaming salesman chanted to me, “Burmeeeese jade,” with a knowing nod. His smile implied that nothing could be better.
Imperial-quality jade. Courtesy of Mason-Kay.
That was about eight years ago, when jade and rubies from Burma (Myanmar) were banned from the United States. Retailers in the U.S. could not sell them. Wholesalers could not import them. Well, that recently changed, and the announcement got me interested in the story of how these gems came to be sanctioned.
It was back in 2003 when George W. Bush signed the trade embargo, prohibiting the import of Burmese goods. The military ruling group, the “junta”, of the country had imprisoned the people’s leader, Aung San Suu Kyi. Citizens of the country were having their human rights violated. The embargo was a response to what was considered an unacceptable way to govern.
But there were loopholes in the 2003 document, and Burmese jade and rubies still found their way into the U.S. If a “middleman” country got involved, either in the cutting or polishing step, it was still legal to import these gems to the U.S. That is, until July 2008.
President Bush signed a new document, the Tom Lantos Block Burmese J.A.D.E.(Junta’s Anti-Democratic Efforts) Act, which closed the loopholes and effectively banned the import of ALL precious Burmese gemstones. Wholesalers and retailers selling ruby and jade needed documentation to certify that the gems had not originated in Burma.
The jewelry industry was negatively impacted by the embargo. Burma was considered the best source in the world for fine ruby and jade. Different sources of the gems had to be found, and, over the years, they were. Today many rubies come from Mozambique. Jadeite sources include Guatemala, Japan, and Kazakhstan.
The trade sanctions had the desired effect. Myanmar began to make reforms in 2010. Over the next couple of years, democratic elections were held and many political prisoners were released. In 2011, the U.S. appointed an ambassador, and, in 2012, President Obama visited the country. Using a cautious approach, President Obama lifted some of the sanctions in November 2012. But the ban on rubies and jade remained in place.
Aung San Suu Kyi, who is now the nation’s State Counsellor (sort of like a Prime Minister), expressed patience, saying that “We believe that if we are going along the right path, all sanctions should be lifted in good time.” And she was right! On October 7th, 2016, President Obama signed an executive order to lift the remaining trade sanctions against Myanmar.
It will be interesting to see how this executive order influences the jewelry industry in the coming months and years. It will take some time to establish or re-establish relationships with Burmese stone dealers. But I believe it won’t be long before we see the deep blood-red Burmese rubies back in our stores. And my “Burmeeeese” jade earrings (Yes. . . I bought them) may soon be easy to find in the United States.
25.59 carat Burmese Ruby, sold in 2015 for $30.3 million
A large polished piece of Greenstone
In late September I was in Swede’s, the famous light blue jewelry and rock store in the middle of Copper Harbor, Michigan. The feisty woman in charge, 83-year-old Mary Billings, asked me as I walked in–“What is the gemstone of Michigan?”
When I answered, “Isle Royale Greenstone,” she looked at me with new respect.
“You’re only the thirteenth customer this season who has answered that question correctly. And we’ve had a lot of people who’ve walked through that door.” She shook her head, a little disgusted that Michiganders weren’t commonly aware of their state gemstone.
Most people, if they have any idea at all, would probably say Petoskey is the state’s gem. And it IS the state rock. But Isle Royale Greenstone, or just Greenstone, has been Michigan’s official gem since 1973. Found mainly on Isle Royale or the Keweenaw Peninsula, Greenstone has the fancy, scientific name of Chlorastrolite, which is a variety of the mineral Pumpellyite. It’s often found in and around copper mines, which are abundant in the Keweenaw. The mineral makes its home in amygdaloidal basalt. If you’re like me, that phrase holds no meaning. I had to look it up, so I’m happy to share its meaning. Basically it’s a pit or cavity in the stone. So amygdaloidal basalt is cooled and hardened lava with lots of cavities in it that have been filled in with minerals.
Once the Greenstone is removed from its host rock, it can be cut and polished. But it’s a tricky stone to work with because it’s not really hard–only a 5-6 on the Mohs’ Scale– and it can have its own cavities and hollow spots within it. Cutters want to expose the best “turtle-back” pattern that they can and eliminate any bad spots. But removing a top layer of the stone is likely to reveal a different, and not necessarily better pattern. The goal is a clear pattern showing some chatoyancy. The best stones will demonstrate that change in luster as they are tilted back and forth in the light.
Tumbled Greenstone with pink Thomsonite
Greenstone is not a particularly expensive gemstone to buy. Even with the labor involved in finding, mining, and cutting it, there’s just not a huge market for the material. But it isn’t an easy gem to own. Since the year 2000, it’s been illegal to take Isle Royale Greenstone off the island. The island is, after all, a national park. And even Keweenaw Greenstone isn’t easy to get unless you have access to the copper mine areas. Most jewelry stores, even in Michigan, don’t carry Greenstone. So plan on spending some time searching for your perfect piece of Michigan’s gemstone. Whether you spend time looking along the shoreline for a rare small piece of it, or whether you search for jewelry stores that carry the gem, enjoy the journey.
My piece of Keweenaw Greenstone! I love it!!
Garnet: January birthstone
Most of my life I’ve wished I was born a few days earlier, mainly because my birthstone would be an emerald instead of pearl or alexandrite. When it came time to buy my high school class ring, I chose the emerald green stone rather than the pale purple one. When my husband and I designed our 30-year anniversary ring, we designed it with an emerald for the center stone, even though pearl is the traditional gift for the 30-year anniversary. As you can see, I’ve always just gone with what I wanted rather than what I was ‘supposed’ to want. But my decisions got me to thinking about the origin of birthstones. Who deemed that each month be represented by a different gemstone? When was this decision made? And why?
My research on these questions has revealed an interesting and somewhat nonsensical journey. Most sources say that the idea of birthstones started with the Bible and Aaron’s breastplate. Aaron had 12 stones in his breastplate, representing the 12 tribes of Israel. No one knows for sure what the 12 stones were, but chances are high that they were pretty rocks, like jasper or lapis. These are rocks that were native to the area.
A first century historian named Josephus supposedly made the numeric connection between the 12 stones and the 12 months of the year. For centuries the idea was to have 12 stones, carrying a different one each month. They weren’t really birthstones because they weren’t associated with the owner’s birth. They were associated with months of the year. The individual stones were supposed to bring good luck and good health during each one’s specific month.
But somewhere along the way, the idea changed. Experts say that between the 15th and 18th centuries, people began to see themselves as having one stone, corresponding to the month of their birth, that would bring them good fortune. These stones, with a few exceptions, are very different from the birthstones of today. Have you ever heard of bloodstone? It’s an opaque green stone with red spots. It was the birthstone for March. How about sardonyx? That’s a banded, rusty brown-colored, translucent chalcedony that was the birthstone for August.
Bloodstone: March birthstone
Sardonyx: August birthstone
In 1912, Jewelers of America, an association with a definite interest in marketing gemstones, sought to standardize the list. The official list of birthstones had garnet, amethyst, aquamarine, diamond, emerald, pearl, ruby, peridot, sapphire, opal, topaz (the orange-yellow-brown kind), and turquoise. Some of the months had two birthstones, partly in deference to the traditional stones. So March had aquamarine AND bloodstone. August had peridot AND sardonyx. But, let’s face it, if you were born in March, which gem would you rather have? A transparent medium blue one or an opaque dark green one with red blemishes? It didn’t take long to drop these traditional choices.
The 1912 list has had few changes in the last 100+ years. In 1952, alexandrite was added as a birthstone for June and citrine was added as a birthstone for November. December’s traditional birthstone of lapis lazuli was replaced with blue zircon. In 2002, tanzanite, the blue-purple gemstone that had been discovered in 1967, was added to the list for December. And, most recently, in 2016, spinel was added as a birthstone for August.
Why the additions? Many people would say it’s a marketing move. Birthstones aren’t really seen as bringing good luck or good health anymore. They don’t have the significance they used to have. They’re just fun. So why not have more choices? I’m really happy for all you August babies who no longer feel confined to the yellowish-green of peridot. Spinel offers great variety! (See my blog on spinel–July 28, 2016).
So, what do we make of this idea of birthstones? To me it sounds like a complicated game of Telephone. Do you remember that game when someone whispers a phrase to someone else, and it goes around the circle? The final uttering of the phrase bears no resemblance to the original. That’s how I feel birthstones came to be. From Aaron’s breastplate to the writings of Josephus to the Jewelers’ list, it’s a crazy, convoluted path. But this is where we are and what we have. My suggestion? Adopt your favorite gemstone, the one that has meaning to you, and make it YOUR birthstone.
Amethyst: February birthstone
Have you ever heard of Crater of Diamonds State Park in Arkansas? The place where you can sift through the dirt and look for the sparkle of a diamond? I so wish my parents had taken me here when I was a kid!! Even though the possibility of finding a diamond is small–only about 1-2% of all visitors leave with one–the probability of having a good time is very high.
Crater of Diamonds has been a state park since the early 1970s. The park encompasses over 900 acres, but 37 of those acres sit on a volcanic pipe. This pipe, which was part of a 95 million year old volcano (long since eroded), carried diamonds to the Earth’s surface. Today, Crater of Diamonds is the only diamond-bearing site that is open to the public. For eight dollars you can search from morning til night. The park has exhibits and videos that give you the history of the area as well as good tips on how to search for diamonds. It has equipment you can rent, things like shovels and sifting screens, or you can bring your own. Over the years the park has been the location for some remarkable stories.
The biggest diamond ever found there, or anywhere in the U.S., was a 40.23 carat stone called Uncle Sam. It was found back in 1924, when the area was still owned by a diamond mine. Other big finds have been made over the years. As recently as 2015, an 8.52 carat diamond was found, and has been named Esperanza. Most of the diamonds found, however, are small. Approximately 90% of the diamonds are less than 1/4 carat, which is only about the size of a match head . The diamonds from this site are yellow, brown, or colorless. They are not easy to find, but one feature that helps is that they look polished, almost as if they have an oily film on them. Also, they’re usually translucent, which means you can see into them but you can’t see through them. If you’re not sure what you’ve found, there is an expert at the site, ready to help you with identification.
The park is a popular place. It had 168,000 visitors last year. In addition to looking for diamonds, there is a water park and camping. It sounds like the place for a perfect day, if you’re a kid. Go get dusty and dirty looking for rocks, and then get cooled and cleaned off at the water park! Heck, it sounds great even if you’re not a kid!!
If you’d rather look for colored gems, amethysts, garnets, and agates have also been found at Crater of Diamonds. But there are, perhaps, better locations in the U.S. if you’re rockhounding for colored gemstones. Check out Gem Mountain in Montana for sapphires. Or Emerald Hollow Mine in North Carolina for emeralds, rubies, and aquamarine. Morefield Mine in Virginia is a source for amazonite, beryl, garnet, amethyst, and topaz.
It’s not too early to start planning next summer’s vacation. Ask your kids and they’ll tell you–“We want to dig for gemstones!”
I have some very good news for all of you born in August. Just recently, the American Gem Trade Association and Jewelers of America announced that SPINEL has been added to the birthstone list as an alternative to peridot. Not everyone is a fan of peridot’s yellowish-green color, and the gem stone has a narrow range of hue. Spinel, on the other hand, comes in almost every color of the rainbow! The most prized color is red. Pink and blue are two other popular hues. So, because spinel is a relatively unknown gemstone and because changes to the birthstone list don’t happen often, it seemed important to write about it.
Many people have never heard of spinel. It was recognized as a separate mineral about 200 years ago, but, until then, red spinel was often mistaken for ruby. Some famous gems, like the Black Prince’s Ruby, which is set in England’s Imperial State Crown, are actually red spinel. Those who have heard of it often associate it with something “cheap” or “common.” Synthetic (aka man-made) spinel has been used for years to make the stones for high school class rings because it’s inexpensive to produce in lots of different colors that mimic birthstones like emerald, ruby, and sapphire. Synthetic spinel is also used as the top, bottom, or both of a “triplet” that substitutes for a natural gemstone.
Natural spinel is a beautiful mineral made of magnesium, aluminum, and oxygen. It’s colorless unless a trace element such as chromium, iron, or cobalt makes its way into the recipe. Chromium leads to a pink or red spinel. Iron and cobalt lead to violet and blue spinels. A combination of trace elements produces orange or purple spinels. These colors need no enhancement, so spinel is rarely heat-treated or irradiated. It’s a fairly hard gemstone, scoring 8 on the Mohs Scale, and it forms in the cubic crystal system. These qualities mean that spinel is hard enough to take a good polish and easy enough to cut and facet. And the gem is usually eye-clean when it comes to inclusions.
Spinel is traditionally associated with Asia–especially Myanmar, Vietnam, and Sri Lanka. More recently deposits have been found in Tanzania and Madagascar. Large crystals are quite rare, so the value goes up exponentially, not only for great color but also for size. While not as expensive as fine ruby or pink sapphire, natural spinel is not an inexpensive gem. Red spinel would cost approximately 30% of the cost of a similarly sized ruby. And pink spinel would be about 85% of the cost of a same size pink sapphire. It’s not easy to find spinel in a jewelry store. Maybe that will change now that it’s a birthstone, but, up until now, it’s been more of a collector’s stone.
So, take heart all of you who longed for another birthstone! It’s spinel to the rescue!! Ask your jewelry store for a peek at its spinel. Here’s a peek at ours.
1.28 carat pink spinel
Flawless Quartz Crystal Sphere at the Smithsonian Natural History Museum (106.75 lbs)
This crystal sphere is the largest cut piece of flawless quartz in the world, weighing in at 242,323 carats! It symbolizes our fascination with something so beautiful and yet so common. Quartz is found around the world, in large quantities, and is considered one of the most common minerals on Earth. It’s found in sand, dirt, and dust. Yet, when fashioned by gem cutters and put in a stunning piece of jewelry, it can be breathtaking.
Quartz is a complicated gemstone. One of the reasons it’s tricky is because the term “quartz” is used for varieties of gems, as well as for a species of gem and as a group of gems. So, for example, Rose Quartz is a variety of the species Quartz. So is Citrine, Amethyst, and Tiger’s Eye! All these varieties, and others that are couched under the species of Chalcedony, such as Agate and Jasper, are considered to be members of the group, Quartz. Very confusing!!
Perhaps it’s best to start with the fact that mineralogists and geologists see any mineral with the chemical makeup of silicon dioxide, SiO2, as Quartz. Regardless of whether the crystals making up that stone are large, small, or microscopic, it’s all Quartz. Gemologists, on the other hand, separate the gems into those whose crystals are larger and those too small to see without a high-powered microscope. Those with larger crystals are called Quartz and those with microcrystalline structures are labeled Chalcedony.
Under these two species are many varieties that are used in jewelry. Probably the most commonly known variety of the quartz species is Amethyst. That regal purple has been admired for centuries. The purple color comes from natural irradiation acting upon a trace element of iron. The saturated, medium to deep reddish purple is the most prized color, but amethyst ranges from a light, pinkish purple to that deep purple hue. Amethyst is not rare, but the prized color is more rare because usually only the tips of the amethyst crystals have that depth of color.
Agate and Amethyst, showing the deep purple tips of the quartz crystals, as well as the microcrystalline Agate, which is part of the Chalcedony species.
Other varieties of the Quartz species include Citrine, the orange-yellow gemstone that’s November’s birthstone, and Rock Crystal, which is colorless because it has no trace elements. There’s also Rose Quartz, Smoky Quartz, Prasiolite (aka Green Amethyst), and Ametrine (a bi-colored gem combining the purple of Amethyst and the yellow of Citrine).
Members the Chalcedony species have been used in jewelry even longer than Amethyst! Agates, which exhibit wavy bands of color, were used in amulets and talismans over 3000 years ago. They were also used to make cameos. Carvers would reveal a differently colored band by carving down around the subject of the piece. Today you’ll see agate slice pendants that are sometimes dyed to accentuate the banding.
Probably the most valuable member of the Chalcedony species is Chrysoprase. This translucent gemstone is beloved for its natural apple-green color. It owes its color to the presence of nickel. A big discovery of Chrysoprase was made in 1965 in Australia. Because its color can resemble fine jadeite, it’s sometimes called “Australian Jade.”
Other varieties of the Chalcedony species include Black Onyx (dyed black chalcedony), Carnelian, Jasper, and Fire Agate. Most chalcedony is translucent to opaque, so it’s rarely faceted. Most often it’s fashioned into beads, slices or cabochons. But, just like all Quartz, it registers a 7 on the Mohs Hardness Scale, making it a good choice for rings and bracelets as well as earrings and pendants.
There’s so much that can be said about this beautiful mineral that surrounds us everyday. But I want to end with the sentiment– “How wonderful when something so common can also be so special!”
Custom-made Ametrine Ring in our showcase!
The romance and history of colored gemstones has always fascinated me. I guess I’m just a sucker for a good story. Here are three I thought you might like.
TANZANITE: It’s said that we are all members of the “Tanzanite generation.” Discovered in 1967 by a Masai tribesman in Northern Tanzania, Tanzanite is mined in only one, 4 square kilometer, location. And the mines are getting deeper and harder to mine profitably. We will be the ones who can buy a new Tanzanite. Future generations will only see the stone in heirloom pieces. It’s estimated that Tanzanite One, the largest Tanzanite mining company, has less than 30 years of production left.
The gemstone was named by Henry Platt, great-grandson of the famous Louis C. Tiffany. Tiffany and Co. realized the importance of the gemstone and quickly made themselves the main distributor. Their marketing efforts made tanzanite one of the most popular gemstones by the 1990s. The beautiful gem hit the big screen with a “splash” as the Heart of the Ocean in the movie, Titanic.
MORGANITE: This pink to orange/pink variety of beryl was originally discovered in Pala, California in the early 1900s. It was named for J.P. Morgan, a great financier and collector of minerals. Tiffany’s gem buyer and gemologist, George Kunz, was the man who named the gem, buying up all he could find for his wealthy client. Incidentally, another pink gemstone, discovered at about the same time, was named Kunzite in honor of George Kunz. So, he got his own gemstone, too!
Morganite is the same species of mineral as Emerald and Aquamarine. Like Aquamarine, it is usually an eye-clean stone that can be cut in larger sizes. It’s a good thing, too, because a larger stone usually shows a more saturated color. Pale Morganite often needs that advantage. It’s generally heat-treated to improve its pink color and minimize its yellowish tint. The treatment is stable, so no fading occurs.
ALEXANDRITE: First discovered in Russia’s Ural Mountains in the early 1830s, Alexandrite is the quintessential color-change gemstone. It was found by miners who thought they’d found emeralds, until nighttime came and they were sitting around the campfire. Alexandrite’s trace elements of iron, titanium, and chromium make it greenish in sunlight and reddish in incandescent or fire light. Boy, were those miners surprised when, the next morning, their red gemstones had turned back to green!
Legend says that the gem was found on the 16th birthday of young Alexander II, future Czar of Russia. The stone became the National Gem of Czarist Russia. It was the perfect fit with the red and green color scheme of imperial Russia’s military. Every Russian had to have an Alexandrite. Unfortunately, for all of us, the Russian supply was depleted. Fortunately, other deposits have been found in Sri Lanka, East Africa, and Brazil.
Natural Alexandrites are very expensive, especially in larger sizes. Even the synthetic version is expensive, because it’s difficult to manufacture. But, if you’re lucky enough to own an Alexandrite, you have an “Emerald by day, and a Ruby by night.”
The general feeling among gemologists and gem merchants is that there is nothing wrong with any type of treatment as long as it’s fully disclosed to the customer, and the customer is being charged appropriately for the treated stone. As discussed in our last blog, many treatments have stable results. Enhancements such as bleaching, irradiation, and heating are commonly accepted by most in the jewelry industry because, not only are they permanent but they are also treatments that could have occurred naturally. Some enhancements, however, are not as stable or they lack that “natural” quality. Gemologists and gemstone merchants are wary of gemstones that have been coated or fracture filled.
Gemstones have been painted or coated for thousands of years. It’s not a new idea. Often the back side (pavillion) or girdle of a faceted gemstone is coated with a thin film of metal oxide paint. The well-known Mystic Topaz is actually colorless topaz with a thin layer of titanium on its pavillion. The coating causes interference with light and leads to Mystic’s rainbow of colors. Drusy quartz is another gem that can get coated with permanent metallic film, using a process called vapor deposition. Both of these processes are permanent as long as the gems aren’t exposed to high heat or chemicals.
If a gem such as emerald has tiny fractures or cavities that reach the surface of the stone, apparent clarity of the gem can be improved by filling the fractures with either oil or wax. Even diamonds or rubies can be fracture filled, although the filling is generally lead glass rather than oil. Glass fillings are more durable than oils or waxes. High heat, acids, or even vigorous cleaning in an ultrasonic cleaner can drain the emerald of its oil. New oil can be inserted but, until it is, the emerald will look like it has more inclusions than it had before. Many gemologists worry more about fracture filled diamonds. Emeralds have been oiled for centuries and bench jewelers know the special care that they need. But diamonds normally handle the heat of the jeweler’s torch. A fracture-filled diamond, however, cannot handle heat, and must be treated differently than a non-treated diamond.
This concludes our three-blog series on gemstones and their treatments. I guess the thought I want to leave you with is, if you’re buying nice gemstones, ask questions. Especially if you decide to buy off the internet, look at the fine print. Fracture-filled diamonds are a “fraction” of the cost, but they require special care and will never be as valuable as a diamond that’s not fracture-filled. Know what you’re buying.
The Earth is very hot–over 10000 degrees Fahrenheit at its core. Over the millions of years that gemstones formed in the earth, some have been subjected to high temperatures. Interestingly enough, this heat can alter the light absorption of the stone, changing its color. Sometimes heat “improves” the color of the stone, perhaps taking a gray, brown, or almost colorless stone and turning it to a cheerful blue or a regal purple.
Man has found a way to heat stones that Earth neglected to heat. The most common types of heat treated gemstones are ruby, sapphire, topaz, tanzanite, and zircon. If you buy one of these stones, you can be quite certain that it’s been heated by man. You’d pay a huge premium to have beautiful color without man-made heat. The time spent heating, the temperature, and the other treatments that may be combined with heat will all vary depending on the raw material.
Non-heat treated tanzanite on the left and heat-treated tanzanite on the right
Our planet also naturally irradiates stones. Irradiation can change the arrangement of the protons, neutrons, and electrons that make up the atoms of the stone. This can alter the color of stones as well. Man has figured out how to irradiate gemstones in order to improve color. They can be treated to high energy radiation at a gamma ray facility that uses cobalt-60 so that there is no residual radioactivity. Diamonds are sometimes irradiated to create beautiful fancy colored diamonds. Colored diamonds can occur naturally, but it’s rare for them to be blue or green. That’s why famous gems like the Hope Diamond or the Dresden Green are so amazing. If you see a blue or green diamond, chances are man has irradiated it. Blue topaz is another irradiated gem stone. It’s the combination of irradiation and heat treatment that brings out that beautiful Swiss or London Blue in topaz.
The sun gave us inspiration for bleaching. Stones often look prettier if they are whiter or less brownish. Pearls and jadeite are both commonly bleached–and not by the sun. The process involves hydrogen peroxide or some type of acid. Pearls, even if they are natural in color rather than dyed, are still often bleached to lighten and brighten the color nature gave them.
Unbleached jadeite on the left and bleached jadeite on the right
Most people in the jewelry industry accept these three treatments. Since heating, irradiating, and bleaching could have all occurred naturally, it seems that man is helping out by making a natural process accessible to more gemstones. And since all of these treatments are permanent, no one has to worry about their gemstone changing over time. Finally, without these treatments, colored gemstones and pearls would be much more expensive and exclusive.
Our final post of this series will be about treatments that are not as commonly accepted. These are treatments you, as the consumer, should definitely be aware of before you buy. Treatments such as surface coating and fracture filling can enhance the look of the stone but may not be permanent. Remember to ask questions if you want to know about treatments on a gemstone you’re planning to purchase.
Lake Superior Agates
If you’re a Michigander like me, you grew up going to one of the Great Lakes for a day at the beach. As a kid, I didn’t know how lucky I was to witness the variety of minerals and rocks along the lakeshore. No where else in the world can you see that variety. I would look for our state rock, the Petoskey stone. I didn’t even know that Michigan had a state gem, the Isle Royale Greenstone (aka Chlorastrolite.)
I’ve always been a rock hound of sorts, and many Michiganders share my passion. There’s so much to know about our rocks and minerals. Most of the information in this post comes from a great book called, Michigan Rocks and Minerals, by Dan and Bob Lynch. I’d highly recommend it if you’re a serious rock hound.
Their book brought up questions I’d never considered before.
*What’s the difference between a MINERAL and a ROCK?
A mineral is a crystallized version of a chemical compound. Most gemstones are minerals. For example, a diamond is crystallized carbon. Quartz is crystallized silicon dioxide. Rocks are a conglomerate of minerals. Lapis Lazuli is an example of a gem that’s actually a rock. Its main ingredient is lazurite, but it also has minerals like calcite, pyrite, and mica. While minerals have characteristics, such as hardness or refractive index, that can be identified throughout the mineral, the characteristics of a rock vary depending on which spot of the rock you’re testing.
*What’s the difference between rock hunting in the Upper Peninsula vs. the Lower Peninsula?
The U.P. and L.P. are geologically very different. The U.P. is formed from volcanic rock. It is rich in the elements of copper, iron, manganese, and even gold. Those elements lend themselves to minerals like azurite, chrysocolla, and hematite. The L.P. is formed from sedimentary rock. It has a lot of limestone, shale, and gypsum. Most of the pretty Michigan minerals, in my opinion, are found in the Upper Peninsula.
*What are some basic tools needed to identify rocks and minerals?
If you do want to do some rock identification, you’ll need a few simple tools. Of course, an identification book is necessary. But one of the main ways to identify a rock is by its hardness. The Mohs Hardness Scale measures minerals from 1 to 10, with one being the softest and ten the hardest. Most minerals in Michigan fall between 2 and 7. You can estimate a mineral’s hardness using a scratch test, taking care to scratch the specimen in an inconspicuous place. Your fingernail will scratch a mineral of 2.5 hardness or less. A copper penny will scratch a mineral of 3.5 hardness or less. A piece of glass or a steel knife works on minerals of 5.5 or less, and a piece of unglazed porcelain works on minerals of 6.5 or less. So these four inexpensive tools can really help you narrow down the options when you want to identify your find.
Michigan Rocks and Minerals discusses over 200 different materials, giving details such as hardness, common size, and color. The book has color photos of the materials and gives suggestions of where to look for them. I’ve decided I want to look for Lake Superior Agates, Dolomite, and Pudding Stones next summer when I go to the U.P. Wish me luck!!