Parakeldyshite

Formula: Na₂ZrSi₂O₇

Origin of name: from Greek para = similar and keldyshite

Crystal system: triclinic

Crystal class: 1

Twinning: 

Unit cell: a = 5.419, b = 6.607, c = 8.806, α = 71.5°, β = 87.15°, γ = 85.63°

Colour: White, slight bluish tinge

Diaphaneity: Translucent

Luster: Vitreous

Habit: Irregular cleavage masses

Hardness: 5.5 to 6

Specific gravity: 3.39

Cleavage: 4; {001} perfect, {110} and {1-10} less perfect, {011} good

Tenacity: 

Streak: White

Synonyms/varieties:

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