Colemanite

Formula:  Ca₂B₆O₁₁ ^. 5H₂O

Origin of name:  For W. Coleman, founder of American borax industry

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 8.72 Ǻ, b = 11.25 Ǻ, c = 6.10 Ǻ, β = 110.1°

Colour:  Colourless, white, yellowish white, greyish

Diaphaneity:

Luster:

Habit:  Crystals equant, short prismatic, pseudo-hexagonal; massive; rounded aggregates

Hardness:  4.5

Specific gravity:  2.42

Cleavage:  2; {010} perfect, {001} distinct

Tenacity:  Subconchoidal to uneven; brittle

Streak:

Synonyms/varieties:

Comments: