Turkestanite

Formula: Th(Ca,Na)₂(K_1-X,[]_X)Si₈O₂₀·nH₂O

Origin of name: Named after the discovery locality, along the Turkestan Ridge.

Crystal system: Tetragonal

Crystal class: 4/m 2/m 2/m

Twinning: 

Unit cell: a = 7.592, c = 14.824

Colour: Apple green to dark green, brownish

Diaphaneity: Transparent

Luster: Vitreous

Habit: Granular, euhedral crystals

Hardness: 5.5-6

Specific gravity: 3.36

Cleavage: [111] imperfect, [111] imperfect, [111] imperfect

Tenacity: Brittle, conchoidal fracture

Streak: White

Synonyms/varieties:

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