| Colemanite | |
|---|---|
 | |
| General | |
| Category | Inoborates |
| Formula (repeating unit) | Ca2B6O11·5H2O |
| IMA symbol | Cole[1] |
| Strunz classification | 6.CB.10 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| 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. |
| 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 | [2][3][4][5][6] |
Colemanite (Ca2B6O11·5H2O)[6] or (CaB3O4(OH)3·H2O)[4] 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.[3]
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.[4] At the time, Coleman had alternatively proposed the name "smithite" instead after his business associate Francis Marion Smith.[7]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Schorn, Stefan; et al. (2021). "Colemanit (Colemanite)". Mineralienatlas.
- ^ a b Klein, Cornelis; Hurlbut, Cornelius S. Jr. (1993). Manual of mineralogy: (after James D. Dana) (21st ed.). New York: Wiley. p. 422. ISBN 0-471-57452-X.
- ^ a b c Colemanite, Mindat.org, retrieved 30 December 2021
- ^ "Colemanite mineral data". Webmineral. Retrieved 30 December 2021.
- ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Colemanite" (PDF). Handbook of Mineralogy.
- ^ Hildebrand, GH. (1982) Borax Pioneer: Francis Marion Smith. San Diego: Howell-North Books. p 31 ISBN 0-8310-7148-6