Aravaipaite

Formula:  Pb₃AlF₉^.H₂O

Origin of name:  Locality; Aravaipa mining district; Arizona

Crystal system:  Triclinic

Crystal class:  1 or -1

Twinning: Polysynthetic on {010}, universal

Unit cell: a = 1.678 Å, b = 25.20 Å, c = 5.652 Å, a = 93.84°, b = 90.14°, g = 85.28°

Colour:  Colourless

Diaphaneity: Transparent

Luster:  Vitreous to pearly

Habit:  Thin lamellar plates 0.001-0.1 mm thick up to 3 mm across

Hardness:  about 2

Specific gravity: 6.37 (calculated)

Cleavage:  5; {010} perfect micaceous; {100}, {001}, {101}, {10-1}good

Tenacity: Flexible

Streak:  White

Synonyms/varieties: Found in the oxidised zone of an epithermal Pb-Cu-Ag deposit hosted by a silicified rhyolite-schist breccia.

Comments: Formed in reaction of supergene solutions on galena and fluorite.