ZARATITE (small cabinet)

Zaratite is a vivid emerald green nickel carbonate mineral represented by the formula Ni3CO3(OH)4·4H2O. It crystallizes within the isometric system, appearing as massive or mammillary encrustations and vein fillings. With a specific gravity of 2.6 and a Mohs hardness ranging from 3 to 3.5, it exhibits no cleavage and is characterized by a brittle, conchoidal fracture. Its luster varies from vitreous to greasy.

This rare secondary mineral forms through the hydration or alteration of primary nickel and iron-bearing minerals such as chromite, pentlandite, pyrrhotite, and millerite during the serpentinization process of ultramafic rocks. A related mineral is hellyerite, with the formula NiCO3·6H2O. Zaratite was first discovered in 1851 at the Manolita mine in Teixedelo, Cedeira, La Coruña province, Galicia, Spain, and is named in honor of the Spanish diplomat and dramatist Antonio Gil y Zárate (1793–1861).