Goslarite

Goslarite is a hydrated zinc sulfate mineral with the formula ZnSO4·7H2O. It forms colorless to white crystals and is commonly found as transparent crystals or crusts with a vitreous luster. Goslarite crystallizes from zinc-rich brines in evaporite or hydrothermal environments. It is relatively soft, with a Mohs hardness near 2, and is readily soluble in water.

Named after the mining town of Goslar in the Harz Mountains of Germany, goslarite was first described there and bears the locality-based name. The mineral occurs in the oxidized zones of zinc-bearing ore deposits and in evaporitic settings, where zinc sulfate-rich fluids crystallize on surfaces of cavities or walls. It is often found associated with other sulfate minerals such as gypsum and epsomite, and with zinc minerals like smithsonite and sphalerite.

Because goslarite is a hydrated mineral, it loses water when heated, converting to less hydrated zinc sulfate phases. The mineral is rare worldwide and is principally of interest to mineral collectors and researchers studying zinc sulfate brines. It is not a major ore of zinc, with commercial zinc production instead relying on other minerals.