Herbertsmithite Locality: Caracoles , Sierra Gorda District, Tocopilla Province , Antofagasta Region , Chile ( Locality at mindat.org ) Size: 4.5 x 4.4 x 2.7 cm. This very rare copper mineral is here present as beautiful sparkling crystals to about .2 mm, like broken green glass sprinkled on a white matrix. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Herbertsmithite
A green zinc-copper hydroxychloride famous to physicists as a 'quantum spin liquid' candidate; named for mineralogist Herbert Smith.
Intro adapted from Wikipedia (CC BY-SA).
Herbertsmithite is an IMA-recognized mineral species in the halide class, with the chemical formula Cu₃Zn(OH)₆Cl₂.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Atacamite structural group.
Key properties: Mohs hardness 3–3.5; specific gravity 3.75–3.95; Vitreous luster; refractive index 1.821; optically uniaxial.
IMA symbol Her, IMA status: approved, named in 2003.
Found as a secondary mineral in the oxidation zone of polymetallic mineral deposits.
It is found associated with Gypsum, opal, dioptase (Chile); wulfenite, hemimorphite, chrysocolla, rosasite, iranite, diaboléite (Iran).
The mineral was named to honor G.F. Herbert Smith (1872-1953), British Museum (Natural History), who discovered paratacamite.