Colemanite

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Colemanite

General
Category Borate mineral
Chemical formula CaB3O4(OH)3·H2O
Identification
Color Colorless, white, yellowish, grey
Crystal habit Massive granular to coarsely crystalline, most commonly nodular.
Crystal system Monoclinic - Prismatic
Cleavage [010] perfect, [001] distinct
Fracture Brittle uneven to subconchoidal
Mohs Scale hardness 4.5
Luster Vitreous
Refractive index nα = 1.586 nβ = 1.592 nγ = 1.614
Optical Properties Biaxial (+)
Birefringence δ = 0.028
Streak White
Specific gravity 2.42
Fusibility 1.5
Diagnostic Features Exfoliates on heating, produces a green flame
Diaphaneity Transparent to translucent
Other Characteristics Bright pale yellow fluorescence, may phosphoresce pale green; pyroelectric and piezoelectric at very low temperature.
References [1][2][3][4]

Colemanite (CaB3O4(OH)3·H2O) is a borate mineral found in evaporite deposits of alkaline lacustrine environments. Colemanite is a secondary mineral that forms by alteration of borax and ulexite.[1]

It was named after William Tell Coleman (1824-1893), owner of the mine Harmony Borax Works near Furnace Creek in Death Valley where it was first found in 1884.

Colemanite
Colemanite

[edit] See also

[edit] References

  1. ^ a b Klein, Cornelis and Cornelius S. Hurlbut, Jr.; 1985, Manual of Mineralogy, Wiley, 20th ed., p. 347 ISBN 0-471-80580-7
  2. ^ http://www.mindat.org/min-1108.html Mindat
  3. ^ http://webmineral.com/data/Colemanite.shtml Webmineral
  4. ^ http://rruff.geo.arizona.edu/doclib/hom/colemanite.pdf Handbook of Mineralogy