Utah Gemstone Mining
Utah is a source for many beautiful and interesting gem materials.
Red beryl is one of the world's rarest gemstones. It is found in a few locations in the Thomas Range and the Wah Wah Mountains of Utah. It is also found in the Black Range of New Mexico. The crystals are generally small, often too small to facet. High-quality rough that is large enough to facet can produce finished stones that sell for as much as $2,000 per carat.
The host rock for red beryl is usually a rhyolitic lava flow. The mineral is thought to form after the lava has cooled into rhyolite and beryllium-rich gases move upwards through shrinkage cracks. Descending groundwater carrying essential elements from above meets the gases, and crystallization occurs.
Beryllium rarely occurs in large enough quantities to produce minerals, and the conditions needed to produce a red color rarely occur. This coincidence of two rare events is why red beryl is found in just a few places on Earth.
Red beryl is known by a number of names. It was first named "bixbite" after Maynard Bixby, who first discovered the gem. It has also been called "red emerald," which is not widely accepted because it causes confusion with the green variety of beryl known as emerald. Red beryl is the most appropriate name.
The Thomas Range of western Utah is also one of the world's best sources of topaz. Cavities in the Topaz Mountain Rhyolite often contain topaz crystals with a beautiful amber color.
Topaz crystals are also found in soils and dry washes around Topaz Mountain. These crystals are usually colorless because the amber color can be lost through prolonged exposure to direct sunlight. A few specimens fade to a beautiful pink color.
Topaz is a popular gemstone around the world and especially in Utah. The Utah Legislature named topaz the state gemstone in 1969. This has increased the local popularity of topaz and has made topaz jewelry an important item in the state's tourist trade.
Related: Places where you can find rocks & gems in Utah
Variscite is a beautiful yellow-green to deep green to blue-green material that often has interesting matrix similar to turquoise. Some people have confused it with turquoise, but it is generally softer and has a lower specific gravity. It is often cut into cabochons and small sculptures. It is soft, with a hardness of only 4.5 on the Mohs Scale. That makes variscite suitable for pendants, pins, earrings, and other jewelry that will not be subjected to abrasion or impact.
Variscite is an aluminum phosphate mineral that is found in a few locations in Utah. It is a secondary mineral found as nodules, fractures, and other cavity fillings, often in igneous rock. Important Utah localities are near the communities of Lucin and Fairfield.
Picasso and Tiffany?
Two really interesting Utah gemstones have the same names as a famous artist and a famous design house.
"Picasso Stone" is a marble that has brown, gray, and black markings that remind people of abstract art. That is how it earned its name - it was named after Pablo Picasso, the famous artist. Picasso stone is a soft material suitable for jewelry and ornamental uses that will not be subject to abrasion. It is used to make tumbled stones, beads, cabochons, and many other gem and ornamental items.
"Tiffany Stone" is a beautiful purple, blue and white rock composed mainly of fluorite, but might also contain opal, calcite, dolomite, quartz, chalcedony, and bertrandite. It is mined at just one location in the world - the Brush Wellman beryllium mine in the Spor Mountains of western Utah. It can be cut into beautiful cabochons, beads and other items. Unfortunately, the name of this stone has nothing to do with Tiffany & Co., the famous design house.
Dinosaur bone is a novelty gem that has been found in many locations in Utah. To be suitable for gem cutting, the bone must be completely petrified, with the cell cavities being completely infilled and the cell walls completely replaced by chalcedony. It can be found in a variety of colors that include brown, yellow, red, green, orange, and black. The most attractive specimens have a high color contrast between the material in the cavities and walls. It is a very popular gem for men's jewelry such as bolos, cuff links, and rings.
There are very strict rules for collecting dinosaur bone and other fossil materials. Know how they apply to any location where you are looking for rocks, gems, minerals, and fossils.
Wonderstone is a welded-vitric tuff with a composition similar to rhyolite. It forms during explosive eruptions when molten rock material is ejected and sticks together upon landing. If it is buried by overlying ejecta while still hot, it will become compacted into a solid glassy material.
The welded tuff that is known as "wonderstone" has been stained by dissolved minerals in groundwaters that flow through the rock long after deposition. Iron oxides in the water stain the tuff to various shades of yellow, orange, brown, red, and maroon. The stains can form concentric bands between water-conducting fractures and other patterns that lead to the name of "wonderstone." A photo of a few wonderstone specimens is shown on this page.
To be useful for lapidary purposes, the wonderstone must be completely vitrified without a grainy, porous texture. Quite a bit of wonderstone has a great appearance but falls short of lapidary grade because of this texture. Inspect closely when buying or collecting. Nice wonderstone can be used to make great cabochons and polished stones in a rock tumbler. Since it is made of feldspar with a Mohs hardness of about 6, it cuts quickly on the diamond or silicon carbide wheel and can be easily scratched when used in jewelry items that receive rough wear.
Agate, Jasper, Opal and More!
Many other gem materials are found in Utah. The state produces a fantastic variety of agates and jaspers and petrified woods. Facetable garnet and amethyst are also found in Utah.
Contributor: Hobart King
|United States Gemstones|
|Ruby and Sapphire|
|Pictures of Opal|
More From Geology.com: