Tamaite

Formula: (Ca,K,Ba,Na)_3-4Mn₂₄(Si,Al)₄₀(O,OH)₁₁₂ ·21H₂O

Origin of name: for the locality, Shiromaru mine, Okutama, Tama district, about 60 km from Tokyo, Japan.

Crystal system: Monoclinic

Crystal class: 2/m

Twinning: 

Unit cell: a = 16.64, b = 27.11, c = 25.35, β = 98.74°

Colour: Colourless, pale yellowish brown

Diaphaneity: Transparent

Luster: Vitreous-pearly

Habit: Micaceous, platy

Hardness: 4

Specific gravity: 2.85

Cleavage: 1; {001} perfect

Tenacity: 

Streak: White

Synonyms/varieties:

Comments: