Vimsite

Formula: CaB₂O₂(OH)₄

Origin of name: for Institute of Mineral Resources, Russia (initials = VIMS)

Crystal system: monoclinic

Crystal class: 2/m

Twinning:

Unit cell: a = 10.02, b = 9.71, c = 4.44, β = 92°

Colour: colourless

Diaphaneity: transparent

Luster: vitreous

Habit: crystals to 2 mm

Hardness: 4

Specific gravity: 2.54

Cleavage: 1; parallel to elongation, perfect

Tenacity: 

Streak: White

Synonyms/varieties:

Comments: dimorphous with uralborite