Colemanite

CaB₃O₄(OH)₃·H₂OIMA symbol: Colegrandfathered

Colemanite is a borate mineral with the formula CaB3O4(OH)3·H2O, crystallizing in the monoclinic system. It has a Mohs hardness of 4-4.5, typically colorless, white, gray or yellow in color, with an adamantine or vitreous luster, a specific gravity of 2.417. Its streak is white.

Photos

Crystallography

Crystal system	monoclinic crystal systemWikidata (CC0)
Space group	P 1 21/a 1
Cell (Å, °)	a = 8.712, b = 11.247, c = 6.091; α = 90, β = 110.12, γ = 90
Cell volume	560.398 Å³, Z = 4
Axial ratios	0.7746:1:0.5416calculated from COD 9004262
Source structure	COD 9004262 (The Canadian Mineralogist, 1993)

Powder X-ray diffraction (calculated)

d (Å)	3.132	3.287	3.844	4.002	5.623	2.89
I/I₀	100	57.4	49.4	42.9	42.6	42.1

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9004262; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)	2.408 g/cm³calculated from COD 9004262
Hardness (Mohs)	4-4.5single sourceDana, System of Mineralogy, 6th ed. (1892)
Specific gravity	2.417 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892)
Color	colorless, gray, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892)
Streak	whitesingle sourceWikidata (CC0)
Luster	adamantine, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892)

Chemistry (calculated)

Molecular weight	205.55 g/molcalculated from the IMA formula
Composition (wt%)	Ca 19.5%, B 15.78%, O 62.27%, H 2.45%

Classification

Nickel-Strunz (10th)	6.CB.10Wikidata (CC0)
Nickel-Strunz (9th)	6.CB.10Wikidata (CC0)