Mineralpedia Details for Colemanite

Colemanite

Named to honor William Tell Coleman, who was one of the initial developers of the borax industry in California, USA. Colemanite itself is an uncommon mineral worldwide, but is often found as a common component of borate deposits that developed in arid, alkaline, lacustrine environments usually in warm temperatures. Localities for Colemanite include several in the United States, Canada, Mexico, Argentina, Kazakhstan, Serbia, Greece, and Turkey. Colemanite will fluoresce a bright, pastel yellow under ultraviolet light and can phosphoresce a pastel green. It is pyroelectric and piezoelectric at low temperatures, and generated a charge in response to changes in temperature in pressure, respectively.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/colemanite.pdf

Formula: CaB₃O₄(OH)₃·H₂O
Crystal System: Monoclinic
Crystal Habit: Blocky, Crystalline - Coarse, Massive - Granular
Cleavage: Perfect, Distinct, None
Luster: Vitreous (Glassy)
Color: colorless, gray, gray white, yellowish white, white
Streak: white
Class: Monoclinic - Prismatic
Fracture: Brittle
Hardness: 4.5
WebMineral: View Colemanite
Mindat: View Colemanite

Colemanite from Boron, Kern Co., California, United States

Large crystals over 1cm in size. The Borax mine in Boron, California is operated by Rio Tinto and is one of the largest Borax mines in the world. Borax was discovered in California in 1872. The Borax mine was established in the 1920's. About 74% of the borax produced is used in glass and ceramics, while another 6% is used in soaps and detergents. Borax is also used in a multitude of other applications. A noted quote by W. T. Schaller in 1930: "The cleanser, the pharmacist, the paper and textile maker, the metallurgist, the brazier, and the jeweler all use borax". These are still valid applications today. Colemanite is a main ore of borax as is Ulexite. Borate deposits probably originated from the concentration of boron rich sediments in large playas as brines. The boron probably was derived from hot springs and fumaroles associated with Tertiary age volcanics.