Bonattite

Bonattite is a rare mineral composed of copper sulfate pentahydrate, with the chemical formula CuSO4·5H2O. It is a hydrated form of copper(II) sulfate and is often found in arid environments or as a secondary mineral in oxidized copper deposits. The mineral typically occurs as small, tabular, or prismatic crystals, often exhibiting a vibrant blue or greenish-blue color. It has a vitreous luster and a Mohs hardness of 2 to 2.5, making it a relatively soft mineral.

Bonattite is known to form efflorescent crusts on rock surfaces, particularly in association with other sulfate minerals. Its formation is favored by conditions of low humidity and high evaporation rates. While chemically identical to chalcanthite, bonattite is distinguished by its crystal habit and often appears more compact or as finer aggregates. It can also be found as a weathering product of copper sulfides.

The mineral is named after the Italian geologist and mineralogist Carlo Bonatti. Significant occurrences of bonattite have been reported in various mining districts worldwide, including Chile, the United States, and Australia. Due to its solubility in water, bonattite is not typically found in wet environments. Its delicate crystalline structure and susceptibility to hydration changes make it a mineral of interest for crystallographic and mineralogical studies.