Gonnardite

Formula:  Na₂CaAl₄Si₆O₂₀ ^. 7H₂O

Origin of name:   For Ferdinand Gonnard, French mining engineer

Crystal system:  Tetragonal

Crystal class:  -42m

Twinning:

Unit cell: a = 13.21 Ǻ, c = 6.62 Ǻ

Colour:   White

Diaphaneity:  Translucent

Luster:  Silky

Habit:   Massive, fibrous, radiating, forming spherules

Hardness:  4.5 to 5

Specific gravity:  2.26

Cleavage:  None

Tenacity:

Streak:

Synonyms/varieties:

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