Wyoming State Mineral
Trona STATUS Unofficial DESCRIPTION Trona is an evaporite mineral, meaning it is composed of sediment left behind after evaporation of saline lakes and rivers. It is a hydrated sodium bicarbonate carbonate and the most common of the sodium carbonates. Trona occurs in non-marine environments as a transparent to translucent mineral that is colorless, white, pale brown, gray, or yellow. STATE SYMBOL One of the most mineral-rich states, Wyoming is the largest producer of several important minerals. The largest trona deposit in the world is in Green River, Wyoming. Trona was deposited there as a precipitate from an ancient freshwater lake. Containing high-sodium volcanic ash, this lake evaporated during the Paleogene period, some 25 to 65 million years ago. The mines in the Green River Formation area produce millions of tons of trona a year. The state contributes 90 to 95 percent of U.S. production of the mineral, which constitutes about 25 percent of world production. While Wyoming does not have an official mineral, trona is representative of the state’s geology and economy. NAME ORIGIN The word trona comes from a Swedish word that was derived from the short form of an Arabic word meaning "natron" or "native salt." The mineral was first described in 1773 from an occurrence in Egypt’s Nile Valley. FORMATION AND OCCURRENCE This mineral is deposited in saline lakebeds and along riverbanks by the evaporation of saltwater. It also forms on mine and cave walls in dry climates. It effloresces, meaning it forms as a powdery crust. Trona can occasionally form in holes created by gas bubbles in volcanic rock. The mineral can occur as transparent, prismatic, well-formed crystals, and also in masses and fibers. In Wyoming, trona forms underground in association with four uncommon minerals: shortite, northupite, bradleyite, and pirssonite. In other localities, trona is associated with other evaporites, such as natron, thermonatrite, halite, borax, glauberite, thenardite, and mirabilite. GEOGRAPHIC DISTRIBUTION In arid regions, trona is widespread. Historically important deposits of this mineral occur in the lower Nile Delta, near Memphis, Egypt, and elsewhere in the Sahara Desert. Kenya: Lake Magadi, Rift Valley Chad: Lake Chad Uganda: Lake Katwe Tanzania: Lake Nyassa Namibia: Otjiwalundo salt pan Botswana: Makgadikgadi salt pans United States: Searles Lake, San Bernardino County, California; Borax Lake, Lake County, California; Owens Lake, Inyo County, California; Little Soda Lake, Churchill County, Nevada; elsewhere in Nevada; and extensive deposits in the Green River Formation of Wyoming, Colorado, and Utah Venezuela: Lagunillas Turkey: Beypazari deposit, west of Ankara Italy: Vesuvius, and at Campi Flegrei, near Naples, Campania USES Trona is a source of sodium carbonate, or soda ash, and the primary source of soda ash in the United States. Most of the rest of the world continues to utilize the Solvay process to produce soda ash, in which sodium carbonate is derived from brine, ammonia, salt, and carbon dioxide. After salt and lime, soda ash is among the first minerals to be used by humans. Egyptians used soda ash over 3,500 years ago. The United States exports soda ash made of trona. Soda ash has many industrial applications. The glassmaking industry uses almost half the soda ash produced; other industries using soda ash include the papermaking, water treatment, chemical, and soap and detergent manufacturing industries. Baking soda, or sodium bicarbonate, is made of trona. Trona’s attractive, well-formed crystals make fine mineral specimens that are of particular interest to mineral collectors. However, since this mineral will dissolve if it comes in contact with water and can dehydrate in dry conditions, specimens of trona should be stored in airtight containers.	Trona Sample Trona Sediment Baking Soda TRONA FACTS Group: Thermonatrite-natron  Chemical Formula: Na3H(CO3)2·2H2O Crystal Structure: Monoclinic Hardness (Mohs): 2½ Color: Colorless, gray-white, light yellow; colorless in transmitted light. Transparency: Translucent Luster: Vitreous Density: 2.14 g/cm3 Streak: White Cleavage: [100] perfect; [111] and [001] indistinct Fracture: Brittle - subconchoidal
	Some data courtesy of the Mineralogical Society of  America Author: World Trade Press