Chemistry: Zinc silicate
Crystal system: Orthorhombic; double termination, but of different orientation (hemimorphic); tabular and thin striated crystals; fan-shaped aggregates; massive material granular or fibrous, banded or stalactitic.
Color: Transparent to opaque; commonly banded blue or green; colorless or white, also violet, gray, yellow and brown.
Hardness: 4.5 - 5
Cleavage: Perfect: 1 direction; Fracture: brittle, conchoidal to sub-conchoidal.
Specific gravity: 3.4 – 3.5
Refractive index: 1.63 mean; 1.614 – 1.636; Biaxial positive; 0.022
Luster: Vitreous, silky to dull.
Dispersion: -
Dichroism: -
Occurrence: Secondary mineral in oxidation; oxidation zone of zinc containing ore bodies; Italy, Mexico, Namibia, Algeria.
Notes
Usually associated with smithsonite; massive may look like smithsonite, chrysocolla or turquoise; colorless (rare); crystals faceted for collectors; massive blue material cut cabochon.
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