Steacyite

Formula: Th(Ca,Na)₂K_1-xSi₈O₂₀ (x = 0.2 - 0.4)

Origin of name: for Harold Robert Steacy, Canadian mineral collector

Crystal system: tetragonal

Crystal class: 4/m 2/m 2/m

Twinning: about [010] axis cruciform

Unit cell: a = 7.583 Å, c = 14.76 Å

Colour: brown

Diaphaneity: 

Luster: vitreous

Habit: crystals elongated

Hardness: 5

Specific gravity: 2.95

Cleavage: none

Tenacity: brittle

Streak: white

Synonyms/varieties:

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