Chalcanthite (, ) is a richly colored

blue-green Blue-green is the color that is between green and blue. It belongs to the cyan family of colors. Variations Cyan (aqua) Cyan, also called aqua, is the blue-green color that is between blue and green on a modern RGB color wheel. The ...

water-soluble

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

mineral . 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. Chalcanthite is a

pentahydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

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 An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conv ...

by either manganese as jokokuite, iron as melanterite, or magnesium as pentahydrite.Mindat Chalcanthite group
/ref> Other names include ''blue stone'', ''blue vitriol'', and ''copper vitriol''.

Uses of chalcanthite

As chalcanthite is a copper mineral, it can be used as an

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 April ...

of copper. However, its ready solubility in water means that it tends to crystallize, dissolve, and recrystallize as crusts over any mine surface in more humid regions. Therefore, chalcanthite is only found in the most arid regions in sufficiently large quantities for use as an ore. Secondarily, chalcanthite, due to its rich color and beautiful crystals, is a sought after collector's mineral. However, as with its viability as an ore, the solubility of the mineral causes significant problems. First, the mineral readily absorbs and releases its water content, which, over time, leads to a disintegration of the crystal structure, destroying even the finest specimens. It is critical to store specimens properly to limit exposure to humidity. Second, higher quality crystals can be easily grown synthetically, and, as such, there is a concern that disreputable mineral dealers would present a sample as natural when it is not.

Associated minerals

Given that chalcanthite is found in oxidized copper deposits, it is frequently found in association with other copper minerals. Frequently associated minerals include: *

Calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratc ...

and its polymorph,

aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including pr ...

, both * Brochantite, *

Chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mo ...

, *

Malachite Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fracture ...

, * Melanterite,

Notes for identification

Chalcanthite's blue color is one of its most notable features, but it is insufficient in identification. Other useful tests include associated minerals,

crystal habit In mineralogy, crystal habit is the characteristic external shape of an individual crystal or crystal group. The habit of a crystal is dependent on its crystallographic form and growth conditions, which generally creates irregularities due to ...

, solubility and subsequent coloring of the water blue. Chalcanthite can also dye materials blue when dissolved in water, and has a peculiarly sweet and metallic taste, although consuming it can induce dangerous copper poisoning. Chalcanthite crystal structure

References

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Mineral Galleries
Hydrates Copper(II) minerals Sulfate minerals Triclinic minerals Chalcanthite group Minerals in space group 2

Uses of chalcanthite

Associated minerals

Notes for identification

See also

References