Macdonaldite

Formula: BaCa4Si16O36(OH)2 . 10H2O

Origin of name:  For G. Macdonald, American vulcanologist

 

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning: 

Unit cell: 

 

Colour:  White to colourless

Diaphaneity: 

Luster:  Vitreous to satiny

Habit:  Crystals acicular, tiny, elongated parallel to a-axis

Hardness:  3.5 to 4

Specific gravity:  2.27

Cleavage:  3; {010} perfect, {001} good, {100} poor (or a fracture)

Tenacity: 

Streak:  White

 

Synonyms/varieties:

 

Comments: 

 

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