zarolachite

Zarolachite is a copper carbonate hydroxide mineral occurring as a secondary product in the oxidation zones of copper ore deposits. It is related to other copper carbonates such as malachite and azurite, but it is distinguished by its characteristic green to blue-green coloration and by botryoidal or crust-like growth forms.

It typically forms as botryoidal aggregates and crusts, with a vitreous to pearly luster. Colors range from emerald green to blue-green, and the mineral is usually opaque to subopaque. It has a Mohs hardness of about 3 to 4 and a pale gray to white streak; cleavage is imperfect.

Zarolachite forms through weathering and oxidation of primary copper sulfide minerals, in environments where secondary copper carbonates accumulate. It is reported in copper districts worldwide and is primarily of interest to mineral collectors.

In practical terms, zarolachite is seldom used in jewelry because of its softness and fragility. It can be collected, displayed, or studied in educational specimens. Handling should minimize exposure to acids, and dust exposure should be avoided to reduce inhalation risk associated with copper minerals.

See also: Malachite; Azurite; Chrysocolla; Copper carbonate minerals.