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A Brilliant Discovery: Gems Mined in the United States
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Friday, October 23, 2015

For years centuries, actually, people have valued precious minerals and gemstones so much that people wore, worshipped, and even stole these articles because of how valuable they were. Heck, people even find gems highly valuable today. As gems and minerals are formed in several ways, it isn’t surprising that gemstones are commonly mined. The gold rush and silver boom were what spurred people to settle the western United States, but numerous other states — Nevada, Oregon, and Montana, among others — are still mined today. Only, people aren’t primarily looking for precious metals anymore, they’re looking for gemstones.

Gemstones mined in the U.S. range in color, size, brilliance, value, and rarity, among other traits. As there are countless gemstones across the world, for this post, we’re only focusing on a few that can be mined in the United States.

o   As opal is (one of) October’s birthstone, this is the gem that’s starting the list. Opal’s internal structure allows this gemstone to diffract light, having a rainbow of internal colors make up its appearance. Precious opals, however, aren’t just white with a rainbow of colors; precious opals can range from white, gray, red, blue, magenta, rose, green, and the most rare, black. In folklore, if a person wearing an opal wasn’t born in October, it’s said to be bad luck.

o   Where it’s mined in the U.S.: Nevada. The Virgin Valley opal fields of northern Nevada are the largest source of precious opals in the U.S.  Nevada even deemed the black fire opal its state gemstone.

o   Rank on the Mohs scale of hardness: 5.5-6

•      Sapphire
o   September’s birthstone, when sapphire first comes to mind, you probably think of a deep, royal blue. However, this gem can be found in a wide spectrum of colors. Blue is the most common color, but sapphires can come in pink, yellow, green, orange, brown, colorless, and padparadscha (a pinkish orange). Sapphires fall under the gem variety of corundum, a hard aluminum oxide (Rubies are also a corundum).

o   Where it’s mined in the U.S.: Montana. The Yogo Sapphire has been found in Yogo Gulch, Montana for more than 100 years. In fact, the Yogo Sapphire can only be found in this area of Montana. North Carolina is another state this gemstone can commonly be found.

o   Rank on the Mohs scale of hardness: 9.0

•      (Oregon) Sunstone
o   While its name implies that it is most likely a shade of yellow, orange, or even red, sunstones can come in those colors, as well as, pink, almost translucent, the rare, deep blue, and the also rare green. The commonly found sunstone is classified as plagioclase feldspar, a tectosilicate rock-forming mineral that occurs as crystals. What makes sunstone all the more interesting is its aventurescence, the metallic glitter that occurs inside sunstone. Sunstone’s aventurescence not only gives it a distinct brilliance, but it is often spangled. Sunstone is sometimes also called “heliolite,” from the Greek words “helios” and “lithos,” which mean “sun” and “stone,” respectively.

o   Where it’s mined in the U.S.: Oregon. The variety known as Oregon sunstone is found in Harney County and eastern Lake County. Oregon sunstone is different than sunstone gems found in other parts of the world because the gems mined in Oregon are found both with and without visible copper platelets. These copper platelets or crystals have only been found in Oregon sunstones; sunstones mined in other parts of the world get their glitter effect from hematite, goethite, or pyrite.

o   Rank on the Mohs scale of mineral hardness: 6-6.5

Surprised to learn there are copious amounts of semi-precious and precious gemstones mined in the U.S.? When you’re in the mining business, these are the subjects you become knowledgeable on.

We’ll be educating you even more on gems that are mined in the U.S. with next month’s blog post!

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