Bityite

Formula:  CaLiAl₂(AlBeSi₂)O₁₀(OH)₂

Origin of name:  From locality; Mt. Bity, Madagascar

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 4.98 Å, b = 8.67 Å, c = 18.74 Å, b = ~ 90°

Colour:  White, yellow, brownish white, colourless

Diaphaneity:  Transparent

Luster:  Vitreous, pearly on cleavage

Habit:  Crystals thin tabular pseudohexagonal; micaceous aggregates, rosettes

Hardness:  5.5

Specific gravity:  3.02 to 3.07

Cleavage:  1; {001} perfect

Tenacity: Uneven fracture

Streak: White

Synonyms/varieties:

Comments:  Easily fusible. Member of the micagroup. Found as a late-stage mineral in lithium-bearing pegmatites