Coquimbite

Formula:  Fe₂(SO₄)₃ ^. 9H₂O

Origin of name:  From locality; Province of Coquimbo, Chile

Crystal system:  Hexagonal

Crystal class:  -3 2/m

Twinning:

Unit cell: a = 10.92 Å, c = 17.14 Å

Colour:  Colourless to pale lavender to purple, yellowish, greenish

Diaphaneity:

Luster:  Vitreous

Habit:  Crystals short prismatic or pyramidal; massive, granular

Hardness:  2.5

Specific gravity:  2.11

Cleavage:  2; {10-11} imperfect, {10-10} difficult

Tenacity:  Subconchoidal to uneven; brittle

Streak: 

Synonyms/varieties:

Comments:  Dimorphous with paracoquimbite; soluble in water