Chalcanthite: Facts About Chalcanthite

Chalcanthite: Facts About Chalcanthite. Beautiful Chalcanthite from Planet Mine, La Paz Co., Arizona
Photo: @Allans_minerals/Instagram

Chalcanthite is a richly colored blue/green water-soluble sulfate mineral CuSO₄·5H₂O. It is commonly found in the late-stage oxidation zones of copper deposits. Due to its ready solubility, chalcanthite is more common in arid regions.

If a Chalcanthite crystal looks to good to be natural, it probably is, as good natural crystals are very hard to come across. Natural Chalcanthite crystals are very rare in nature.

Well-formed crystals are easily grown synthetically from copper sulfate solutions. This can be done by dissolving a readily available chemical salt called copper sulfate, and then letting the water evaporate.

Chalcanthite is a pentahydrate and the most common member of a group of similar hydrated sulfates, the chalcanthite group. These other sulfates are identical in chemical composition to chalcanthite, with the exception of replacement of the copper ion by either manganese as jokokuite, iron as siderotil, or magnesium as pentahydrite.

Its blue crystals dehydrate to an opaque greenish-white powder on exposure to dry air.

Chalcanthite specimens must be kept away from water and moist conditions, since a chemical effect with water causes them to eventually crumble or dissolve.

Locality
In the U.S., the most prominent locality for Chalcanthite specimens is the Planet Mine, La Paz Co., Arizona. Other Arizona occurrences include Bisbee, Cochise Co.; Ajo and Tiger, Pinal Co.; Globe, Gila Co.; Morenci, Greenlee Co; and the Patagonia District, Santa Cruz Co. Also occurs in Bingham Canyon, Salt Lake Co., Utah; and Ducktown, Polk Co., Tennessee.

Note of caution: Chalcanthite is poisonous and should not be taste-tested, unless the lick is minor and it is spit out and rinsed immediately.

See also:
Crystal Habits and Forms
Chrysanthemum Stone: Natural Flower Stone