Utah State Gem - Topaz

Sego Lily along the Bonneville Shoreline Trail, 6/16/2010, Photo by Staci Card Green

The Topaz became the State Gem in 1969 (Utah Code). It is a semiprecious gem found in Beaver, Juab and Tooele counties of Utah. Small perfect crystals are found with quartz, hematite, bixbyite, garnet, pseudobrookite, amethyst, cristobalite, durangite, cassiterite and red beryl in cavities in rhyolite on Thomas Mountain, Juab County.

This hard gem is an aluminum fluorisilicate and is next in hardness to carborundum and diamonds (two of the hardest natural minerals around). Until the 1950s, topaz was generally known as a yellow or golden gemstone. Since then, routine radiation and heat treatment of pale-colored topaz to turn it blue has changed the modern public's perception of this gem. Constructed of atoms of aluminum, silicon, fluorine, and oxygen, topaz usually is colorless to pale blue or yellow -- although pink stones can be produced by heating the golden brown topaz from Ouro Preto, Brazil.

Thomas Range topaz obtained their color from natural radiation during their formation in vent pipes which trapped volatile gases in cavities within the host rhyolites. When unearthed they glow with a vibrant sherry color and with exposure to direct sunlight for awhile will generally turn clear. The sunlight (also UV radiation) reacts with the color centers in the topaz crystal structure displacing electrons which in turn change the color. However, some locations do produce topaz that fade to a beautiful pink color. Some topaz are "tougher" than others and do not have as weak a cleavage plane as the Thomas Range topaz which usually they cleave with a flat top. A favorite location for the mineral collectors and rockhounds is called "The Cove" on the southern end of the Thomas Range.

Wear topaz only if you wish to be clear-sighted: legend has it that it dispels all enchantment and helps to improve eyesight as well! The ancient Greeks believed that it had the power to increase strength and make its wearer invisible in times of emergency. Topaz was also said to change color in the presence of poisoned food or drink. Its mystical curative powers waxed and waned with the phases of the moon: it was said to cure insomnia, asthma, and hemorrhages. Topaz is the birthstone of November.

The topaz specimen pictured is from the Maynard Claims, Juab County and is about 3 inches tall. Photo of this Utah born topaz courtesy of Walter Mroch, Gem and Mineral Exploration Company, co-author of A Field Guide to Topaz and Associated Minerals of the Thomas Range, Utah (Topaz Mountain), volume 1.

Utah's Topaz

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