Antarcticite

Formula:  CaCl₂^.6H₂O

Origin of name:  Locality; in Antarctica

Crystal system:  Hexagonal

Crystal class:  32

Twinning:

Unit cell: a = 7.89-7.907 Å, c = 1.490-1.500 Å

Colour:  Colourless

Diaphaneity: Transparent

Luster:  Vitreous

Habit:  Large acicular aggregates

Hardness:  2 to 3

Specific gravity:  1.72

Cleavage:  {0001} perfect

Tenacity: Brittle

Streak: White

Synonyms/varieties:

Comments: Formed as a precipitate from highly saline brines under very arid conditions; in stratified fresh to brackish to salt water columns in onshore "blue holes"; an abundant component of inclusions in quartz in a zoned mafic pegmatoid (Bushveld complex, South Africa).