Natrochalcite Locality: Chuquicamata Mine, Chuquicamata District, Calama , El Loa Province , Antofagasta Region , Chile ( Locality at mindat.org ) Size: small cabinet, 7.3 x 5.5 x 4.5 cm Natrochalcite This is a rare hydrated, hydroxyl, sulfate, of sodium and copper that occurs primarily in arid areas, like Chuquicamata. The emerald green natrochalcite, in translucent crystals to .7 cm across, is color contrasted with its whitish-green matrix. Some crystals are obviously damaged but overall the piece is exceptionally rich and colorful, so you can put up with it at the right price. This is another mineral species that never appears in dealers stocks. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Natrochalcite
Natrochalcite is an IMA-recognized mineral species in the sulfate class, with the chemical formula NaCu₂(SO₄)₂(OH)·H₂O.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Natrochalcite structural group.
Key properties: Mohs hardness 4.5; specific gravity 3.49; Pale greenish streak; Vitreous luster; optically biaxial.
IMA symbol Nch, grandfathered status — known before the IMA’s founding, named in 1908.
A rare mineral typically formed in an arid climate in the oxidized zone of copper deposits.
It is found associated with Kröhnkite, antlerite, brochantite, chalcanthite, blödite, atacamite, gypsum (Chuquicamata, Chile); kröhnkite, brochantite (Capo Calamita, Italy).
The name comes from the Latin for sodium, natrium, and the Greek for copper, chalkos, in the composition.