Mesolite

Formula:  Na₂Ca₂Al₆Si₉O₃₀ ^. 8H₂O

Origin of name:  From Greek for middle

Crystal system:  Orthorhombic

Crystal class:  mm2

Twinning:  Common on {010} or {100}

Unit cell: a = 18.40 Å, b = 56.66 Å, c = 6.54 Å

Colour:  Colourless, white

Diaphaneity: 

Luster:  Vitreous, silky when fibrous

Habit:  Crystals acicular or fibrous, in divergent sprays, tufts or masses with radiating structure

Hardness:  5

Specific gravity:  2.259

Cleavage:  2; {101} and {10-1} perfect

Tenacity:  Uneven; brittle

Streak: 

Synonyms/varieties:  Pseudomesolite

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