Caledonite

Formula:  Pb₅Cu₂(CO₃)(SO₄)₃(OH)₆

Origin of name:  Locality; Caledonia (Scotland)

Crystal system:  Orthorhombic

Crystal class:  mm2

Twinning:

Unit cell: a = 20.09 Ǻ, b = 7.143 Ǻ, c = 6.564 Ǻ

Colour:  Dark green, bluish green, blue

Diaphaneity:

Luster:  Vitreous to resinous

Habit:  Crystals elongated prismatic, in divergent groups; massive, thin coatings

Hardness:  2.5 to 3

Specific gravity:  5.76

Cleavage:  3; {010} perfect, {100} and {101} imperfect

Tenacity:  Uneven; brittle

Streak:  Greenish white, blue

Synonyms/varieties:

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