Austinite

Formula:  CaZn(AsO₄)(OH)

Origin of name:  For Austin flint Rogers (1877-1957), American mineralogist, Stanford University, Palo Alto, California, USA

Crystal system:  Orthorhombic

Crystal class:  222

Twinning:

Unit cell: a = 7.506 Å, b = 9.046 Å, c = 5.932 Å

Colour:  Colourless, white, pale yellow, bright green, brown

Diaphaneity: Translucent to transparent

Luster:  Subadamantine to silky in aggregates

Habit:  Crystals tiny, prismatic or acicular; drusy crusts; radial-fibrous nodules

Hardness:  4 to 4.5

Specific gravity  4.13

Cleavage:  1; {011} good

Tenacity:  Brittle

Streak: White

Synonyms/varieties:

Comments:  Forms series with conichalcite. Member of the adelite group. Formed as a rare secondary mineral in the oxidised zone of some arsenic-rich base-metal deposits.