hydrozincite

Hydrozincite is a basic zinc carbonate mineral with the chemical formula Zn5(CO3)2(OH)6. It forms as a secondary mineral in the oxidized zones of zinc ore deposits, commonly in the alteration halos of sphalerite and smithsonite. It occurs as white to colorless crystals or as white crusts and botryoidal aggregates; impurities can give blue, green, or yellow hues.

It has a vitreous to pearly luster and ranges from transparent to translucent in appearance. On the Mohs scale, its hardness is about 3.5–4, and it has a relatively low density around 3.5 g/cm3. The mineral typically forms prism-like crystals and fibrous to granular aggregates, and is often found in radiating or tabular habits, though it is more commonly encountered as crusts on host rocks.

Hydrozincite is part of the carbonate mineral group and represents a basic zinc carbonate, containing hydroxide groups. It is commonly associated with other secondary zinc minerals such as smithsonite and hemimorphite, and can also occur with calcite and quartz.

Economically, hydrozincite is not a principal ore of zinc but is of interest to mineral collectors and serves as an indicator of zinc mineralization in hydrothermal and oxidized environments. It can be produced synthetically by precipitation from solutions containing zinc salts, carbonate, and hydroxide.