Colemanite

Lustre: Vitreous.
Hardness: Mohs 4.5 — soft; a knife will scratch it.
Streak: White.
Habit: Monoclinic crystal system.

Colour	White, Clear
Mohs hardness	4.5
Lustre	Vitreous
Streak	White
Crystal system	Monoclinic
Transparency	Transparent to translucent
Cleavage	[010] perfect, [001] distinct
Fracture	Brittle uneven to subconchoidal
Chemical formula	Ca 2 B 6 O 11 ·5H 2 O
Specific gravity	2.42

What is Colemanite?

Colemanite (Ca2B6O11·5H2O) or (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.