2.1" Vibrant Blue Chalcanthite - Planet Mine, Arizona

Natural chalcanthite can be hard to come by and is considered relatively rare. Its chemical composition is CuSO4 · 5H2O, meaning it forms in oxidative zones of copper mines. When naturally formed, the crystals are usually botryoidal, tabular and/or prismatic in shape. Chalcanthite crystals are also known to form in veins as masses of parallel fibrous crystals, and will typically display a vibrant blue coloration.

Chalcanthite crystals are relatively simple to form synthetically: unfortunately, this means that fake specimens listed as natural are on the market.

One additional note: best not to leave it in direct sunlight. It will begin to decompose fairly rapidly in high heat.