Creedite

Formula:  Ca₃Al₂(SO₄)(F,OH)₁₀ ^. 2H₂O

Origin of name:  Locality; near Creede, Colorado

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 13.91 Å, b = 8.58 Å, c = 10.00 Å, β = 94.4°

Colour:  Colourless, white, amethystine, pink, purple

Diaphaneity:

Luster:  Vitreous

Habit:  Crystals short prismatic to acicular in sprays or clusters; drusy knobby masses, radiating aggregates, embedded

Hardness:  4

Specific gravity:  2.713

Cleavage:  1; {100} perfect

Tenacity:  Brittle

Streak:

Synonyms/varieties:

Comments: