THE MINERAL TRONA

Chemistry: Na₃(HCO₃)(CO₃) - 2H₂O , Hydrated Sodium Bicarbonate Carbonate.
Class: Carbonates
Uses: Only as mineral specimens.
Specimens

Trona is the type mineral so-to-speak for several sodium carbonates that form in non-marine evaporite deposits. Other sodium carbonates include gaylussite, natron, pirssonite, northupite, nahcolite and thermonatrite. Trona is probably the most common and well known of these minerals. They are all difficult to tell apart from each other except when good crystal form is present or when optical or X-ray techniques can be used. All are subject to dehydration and/or hydration to one degree or another and should be stored in sealed containers for this reason. All may form as efflorescent crusts on the walls of caves and mines or in soils in arid regions. Trona gets its name from a discarded Arabic word for native salt, "tron", which is derived from the word "natrun".

PHYSICAL CHARACTERISTICS:

Color is gray, colorless, white, pale brown or yellowish.
Luster is vitreous.
Transparency: Crystals are transparent to translucent.
Crystal System is monoclinic; 2/m.
Crystal Habits include prismatic to blocky crystals, but usually massive, fibrous or columnar.
Cleavage is perfect in one direction and poor in two others.
Fracture is subconchoidal to uneven.
Hardness is 2.5 - 3.
Specific Gravity is 2.1 (well below average)
Streak is white.
Other Characteristics: Has an alkaline taste.
Associated Minerals include hanksite, gaylussite, halite, pirssonite, northupite, nahcolite, borax and calcite.
Notable Occurrences include Searles Lake, San Bernardino County; Borax Lake, Lake County; Owens Lake, Inyo County and Mono Lake, Mono County, California and Green River, Wyoming, USA; Iran; Tibet; Mont Saint-Hilaire, Quebec, Canada and Mongolia.
Best Field Indicators: environment of formation, color, cleavage, density, crystal habit, taste and locality.