Hydrozincite, also known as zinc bloom or marionite, is a white carbonate mineral consisting of Zn<sub>5</sub>(CO<sub>3</sub>)<sub>2</sub>(OH)<sub>6</sub>. It is usually found in massive rather than crystalline form.
It occurs as an oxidation product of zinc ores and as post mine incrustations. It occurs associated with smithsonite, hemimorphite, willemite, cerussite, aurichalcite, calcite and limonite.