Mineral Type - Chrysocolla

A mineral of secondary origin, commonly associated with other secondary copper minerals, it is typically found as glassy botryoidal or rounded masses or bubbly crusts, and as jackstraw mats of tiny acicular crystals or tufts of fibrous crystals. Copper-bearing allophane can look similar.

Name

The name was first used by Theophrastus in 315 B.C. and comes from the Greek chrysos, meaning "gold," and kolla, meaning "glue," in allusion to the name of the material used to solder gold. André-Jean-François-Marie Brochant de Villiers revived the name in 1808.

Physical Properties

Lustre: Vitreous, Waxy, Earthy
Transparency: Translucent, Opaque
Colour: Green, bluish green, blue, blackish blue to black, or brown and rarely yellow
Streak: Light green
Hardness: 2½ - 3½ on Mohs scale.
Tenacity: Brittle
Cleavage: None Observed None
Fracture: Irregular/Uneven, Sub-Conchoidal
Density: 1.93 - 2.4 g/cm3 (Measured)

Chemical Properties

Formula: Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O
Elements listed: Al, Cu, H, O, Si

Crystallography

Crystal System: Orthorhombic
Cell Parameters: a = 5.7 Å, b = 8.9 Å, c = 6.7 Å
Unit Call V: 339.89 ų (Calculated from Unit Cell)
Morphology: Most often found as cryptocrystalline to amorphous botryoidal aggregates and crusts. Crystals reported as fine acicular to fibrous, very rare
Twinning: None reported

Synonyms

Abdollah-Giw Turquoise, Beaumontite (of Jackson), Chalcostaktite, Chalkostaktite, Chrysocole, Chrysocollite, Chrysokolla, Copper Pitchblende, Crysocolla, Demidovite, Dillenbergite, Liparite (of Casoria), Llanca, and Somervillite (of Dufrénoy)

Varieties

Aluminian Chrysocolla, Alumimian Ferrian Chrysocolla, Cornuite (of Rogers), Cyanochalcite