Colemanite

For the community in California formerly named Colemanite, see Ryan, California.
Colemanite
General
Category Inoborates
Chemical formula CaB3O4(OH)3·H2O
Strunz classification 06.CB.10
Crystal symmetry Monoclinic 2/m
Unit cell a = 8.712(2) Å, b = 11.247(3) Å, c = 6.091(1) Å; β = 110.12°; Z = 4
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
Streak White
Diaphaneity Transparent to translucent
Specific gravity 2.42
Optical properties Biaxial (+)
Refractive index nα = 1.586 nβ = 1.592 nγ = 1.614
Birefringence δ = 0.028
Fusibility 1.5
Diagnostic features Exfoliates on heating, produces a green flame
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 first described in 1884 for an occurrence near Furnace Creek in Death Valley and was named after William Tell Coleman (1824–1893), owner of the mine Harmony Borax Works where it was first found.[2] At the time, Coleman had alternatively proposed the name "smithite" instead after his business associate Francis Marion Smith.[5]

See also

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. ^ a b 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
  5. ^ Hildebrand, GH. (1982) Borax Pioneer: Francis Marion Smith. San Diego: Howell-North Books. p 31 ISBN 0-8310-7148-6

External links

 Chisholm, Hugh, ed (1911). "Colemanite". Encyclopædia Britannica (11th ed.). Cambridge University Press.