Formula: Ca[B₃O₄(OH)₃] · H₂O

Species: Borates

Colour: Colourless, white, yellowish, grey; colourless in transitted light

Lustre: Adamantine, Vitreous

Hardness: 4½

Specific Gravity: 2.423

Crystal System: Monoclinic

Name: Named in 1893 in honor of William Tell Coleman (1824-1893), a founder of the California borax industry and owner of the mine where the mineral was first found.

Type Locality: Furnace Creek Mining District (Furnace Creek Borate Mining District), Inyo Co., California – USA