Aurichalcite

Formula:  (Zn, Cu)₅(CO₃)₂(OH)₆

Origin of name:  From Latin aurichalcum = yellow copper or brass ore

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 13.82 Å, b = 6.41 Å, c = 5.29 Å, b = 101.1°

Colour:  Pale green, greenish blue, shy-blue

Diaphaneity: Transparent

Luster:  Silky to pearly

Habit:  Crystals acicular or lath-like; tufted aggregates or crusts

Hardness:  1 to 2

Specific gravity:  3.96

Cleavage:  1; {010} perfect

Tenacity:  Brittle

Streak: Light blue

Synonyms/varieties:

Comments: Secondary mineral in copper and zinc deposits