Davyne

Formula:  (Na,Ca,K)₈Al₆Si₆O₂₄(Cl,SO₄,CO₃)_2-3

Origin of name:  For Sir Humphery Davy, English chemist

Crystal system:  Hexagonal

Crystal class:  6/m

Twinning:

Unit cell: a = 12.705, c = 5.368

Colour:  Colourless to white

Diaphaneity:  Transparent

Luster:  Vitreous

Habit:  Crystals prismatic, minute, striated vertically

Hardness:  6

Specific gravity:  2.42 to 2.53

Cleavage:  2; {10-10} perfect, {0001} poor

Tenacity: Brittle conchoidal fracture

Streak: White

Synonyms/varieties:

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