Alumotantite

Formula:  AlTaO₄

Origin of name:  From aluminum and tantalum in the composition

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning:

Unit cell: a = 4.473-4.477 Å, b = 11.308-11.309 Å, c = 4.767-4.775 Å

Colour:  Colourless to white

Diaphaneity: Transparent to translucent

Luster:  Adamantine to greasy

Habit:  Euhedral to anhedral crystals to 1 mm, elongated with rhombic to rectangular cross-section. As rims on Simpsonite and Natrotantite

Hardness:  7.5 to 8

Specific gravity: 7.48 (calculated)

Cleavage:  None

Tenacity:

Streak:

Synonyms/varieties:

Comments: Found in albitised areas of highly fractionated rare element-enriched granite pegmatites.