Hectorite

Formula:  Na_0.3(Mg,Li)₃Si₄O₁₀(F,OH)_{2 .} xH₂O

Origin of name:   After locality; Hector bentonite mine, San Bernardino Co., California

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning: 

Unit cell: a = 5.25, b = 9.18, c = 16, β = 99°

Colour:  White

Diaphaneity: Translucent to opaque

Luster:  Dull, earthy

Habit:  Massive, fine-grained; clay-like

Hardness:  1 to 2

Specific gravity:  2 to 3

Cleavage:  1; {001} perfect

Tenacity: Uneven

Streak: White

Synonyms/varieties:

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