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Idaho Opal
Opal has been found at many locations in Idaho, and mines there have produced it since the early 1900s. Most of the production has been from small mining operations and open cuts worked by two or three people. There have also been a few fee mining locations where individuals can pay a fee, search for opal, and…
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Gem-Quality Garnet
Gem-quality garnets have been found in the sediments of many Idaho streams. They are mostly deep red almandite and purplish red almandite-spessartite. The most interesting surprise was the discovery of star garnets. These purplish red almandite garnets contain fine rutile needles that produce four-ray stars or six-ray stars when the rough is properly oriented and cut into cabochons. Cutting…
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Garnet Abrasives
People have been searching the stream gravels of Idaho for garnets since the late 1800s, but commercial production did not begin until the early 1940s. At that time, thin gravel layers in the sediments along Emerald Creek, Carpenter Creek, and Meadow Creek in the Idaho panhandle were being mined for garnet abrasive. The gravel layers…
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Idaho Garnet
Garnet in Idaho is found in pegmatites, garnetiferous schists, mica schists, and other metamorphic rocks. It can be removed from these rocks or found in the soils that have formed above them. However, most of the garnets that have been produced in Idaho have been from the sands and gravels of placer deposits. This is where they can be…
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A Diversity of Gems from Idaho
Idaho’s nickname is “The Gem State.” It has a long history of producing a variety of gem materials. The most important gems produced to date have been garnet and opal. Notable amounts of jade, topaz, zircon, and tourmaline have also been found in Idaho. Agate, jasper, and petrified wood in many colors and patterns have been found and produced from small deposits in many parts of the state.
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Ending Some of the Turquoise Confusion
Howlite and magnesite can easily be separated from turquoise using a refractometer. They have different refractive indexes. If you are willing to do a destructive test, the blue dye used to color howlite and magnesite generally does not penetrate very deep. If lightly dyed, scratching the back of a cabochon with a pin will often…
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Look-Alike Materials
Howlite and magnesite are light gray to white minerals that often have markings that resemble the spider webbing seen in some turquoise. They can be dyed a turquoise blue color that makes them look very similar to natural turquoise. These dyed stones fooled many people when they first entered the marketplace and still are mistaken…
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Synthetic and Imitation Turquoise
A small amount of synthetic turquoise was produced by the Gilson Company in the 1980s, and some of their material was used to make jewelry. It was produced in a sky blue color, sometimes with a gray spider webbing. It was a ceramic product with a composition similar to natural turquoise. Synthetic turquoise and turquoise…
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Natural and Treated Turquoise
Only a small amount of turquoise that is mined today can be used to cut finished stones or make jewelry without some type of treatment. These treatments make the turquoise stable enough for cutting, durable enough for jewelry, or improve its color and marketability. Untreated turquoise is a rare commodity. The rough, the stones cut…
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Turquoise Jewelry and Art
The earliest record of turquoise being used in jewelry or in ornaments is from Egypt. There, turquoise has been found in royal burials over 6000 years old. About 4000 years ago, miners in Persia produced a blue variety of turquoise with a “sky blue” or “robin’s-egg blue” color. This material was very popular and traded…