Natrochalcite is a hydrous sodium copper hydroxy-sulfate mineral, NaCu2(SO4)2(OH)ĚH2O. It is a secondary mineral that forms in some copper deposits. It has a nonmetallic, somewhat glassy luster, an intensely green color, pale greenish streak, and is moderately hard (H=4.5). Crystals are transparent to translucent and have monoclinic symmetry. Natrochalcite has perfect cleavage but also readily breaks along uneven fracture surfaces. This minerals is soluble in water and acids.
Natrochalcite from the Chuquicamata Mine, Calama, El Loa Province, Antofagasta region, Chile. (CSM # 720.4, Colorado School of Mines Geology Museum, Golden, Colorado, USA)