Colemanite

Formula: Ca₂B₆O₁₁·5H₂O
Mineral class: borates
Crystal system: monoclinic
Mohs scale: 4.5
Density (g/cm³): 2.42
Refractive index: 1.586 - 1.614
Cleavage: perfect - distinct
Colors: colorless, white, grey, yellowish, orange, brown
Transparency: transparent - translucent
Luster: vitreous - adamantine
Fluorescence: light yellow
Pleochroism: -
Largest crystal: 30 cm?
Deposits: worldwide
Discovery: 1884
1st Description: 1884
Name: in honor of William Tell Coleman (1824 - 1893), U.S. borax industry pioneer

Colemanite Mineral

Size: 4.5 x 4.0 x 3.0 cm

Origin: Billie Mine / Boron / Kern County / California / USA

Photo by kind permission of © Michael C. Roarke

Colemanite

Weight: 0.39 ct

Origin: Billie Mine / Boron / Kern County / California / USA

Photo by kind permission of © www.thegemtrader.com

Colemanite Mineral

Size: 13.0 x 12.5 x 9.3 cm

Origin: Thompson Mine / Darwin / Inyo County / California / USA

Photo by kind permission of © www.irocks.com

Colemanite Mineral

Size: 6.6 x 4.4 x 3.6 cm

Origin: Thompson Mine / Darwin / Inyo County / California / USA

Photo by kind permission of © www.irocks.com

Colemanite Mineral

Size: 8.0 x 4.8 x 6.3 cm

Origin: Kurtpinari Mine / Sultancayin / Faras / Balikesir Prov. / Turkey

Photo by kind permission of © www.fabreminerals.com