antlerite

Antlerite is a naturally occurring basic copper sulfate mineral with the chemical formula Cu3(SO4)(OH)4. It is a relatively rare secondary mineral, meaning it forms through the alteration of other copper-bearing minerals, typically in arid or semi-arid environments. Antlerite is often found in the oxidized zones of copper deposits.

Crystallographically, antlerite belongs to the monoclinic crystal system. It commonly appears as acicular or prismatic crystals, often forming radiating aggregates or crusts. The mineral's color is typically a characteristic emerald green to apple green, and it has a vitreous luster. Antlerite is known to be brittle and will fracture conchoidally. It is relatively soft, with a Mohs hardness of 3 to 3.5, and has a specific gravity of around 3.1 to 3.3.

The mineral was first discovered in the Antler Mine in Mohave County, Arizona, United States, and it was named after this locality in 1911. While it can be found in various locations worldwide, significant occurrences include Chile, Namibia, and Australia, often associated with other copper minerals like malachite, azurite, and brochantite. Antlerite is not typically considered an economically important ore of copper due to its rarity and the presence of more abundant copper minerals, but it is of interest to mineral collectors and geologists studying supergene enrichment processes.