Alumotungstite

Formula:  (W,Al)(O,OH)3

Origin of name:  From aluminum in composition and in analogy to ferritungstite

 

Crystal system:  Cubic, may be rhombohedral, pseudocubic

Crystal class:  Unknown

Twinning: Interpenetrant octahedra may represent twins on {111}

Unit cell: a = 10.20 Å

 

Colour: White

Diaphaneity: Semi-transparant

Luster:

Habit:  Crystals euhedral octahedral, microscopic; aggregated into rounded groups, often intimately intergrown with yttrotungstite and ferritungstite

Hardness:

Specific gravity: 4.52 (calculated)

Cleavage:  None

Tenacity:

Streak:

 

Synonyms/varieties:

 

Comments:  Al analogue of ferritungstite. Observed in fine-grained aggregates of yttrotungstite, also lining cavities relict after ferberite, which has replaced scheelite.

 

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