“Calamine” is not a mineral, but rather a mining term applied to Zn ores composed of smithsonite, hemimorphite, and hydrozincite. For some authors, willemite is also part of “calamine.” The term was coined in 1747 by Johan Gottschalk Wallerius (Vallerius).

It forms a generally white, transparent to translucent rock with a vitreous luster (it can be earthy), often consisting of a mixture of very small crystals of the three minerals mentioned above, as well as associated impurities such as goethite. The colors vary considerably; calamine can be blue, green, red, greenish, pink, or orange. When in cavities, it forms well-developed botryoidal aggregates, similar to those of chalcedony and opal.

Distinguishing the three minerals is impossible in a hand specimen and even under a microscope it can be difficult. Smithsonite and hemimorphite, for example, are so similar to each other that for centuries they were considered a single mineral.

Calamine is an alteration product of sphalerite and other zinc sulfides, associated or not with lead sulfides (galena and others).