Chalcanthite (, ) is a richly colored

blue-green Blue-green is the color between blue and green. It belongs to the shades of cyan, cyan family. Variations Cyan Cyan is the blue-green color that is between blue and green on a modern RGB color model, RGB color wheel. The modern RGB co ...

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 In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

. It is commonly found in the late-stage oxidation zones of

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

deposits. Due to its ready solubility, chalcanthite is more common in arid regions. 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 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 convent ...

by either

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

as jokokuite,

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

melanterite Melanterite is a mineral form of hydrous iron(II) sulfate: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite. It alters to siderotil by Dehydration, loss of water. It is a secondary sulfate mineral which forms from the oxida ...

, or

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

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 including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

of copper. However, its ready solubility in

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

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

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s, 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 minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

and its polymorph,

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

, both *

Brochantite Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is Cu4SO4(OH)6. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it was named by Armand Lévy (mineralogist), Armand Lévy for his ...

, *

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 Mohs scale, hardness of 3.5 to 4 ...

, *

Malachite Malachite () is a copper Carbonate mineral, carbonate hydroxide mineral, with the chemical formula, formula Basic copper carbonate, Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often for ...

, *

Melanterite Melanterite is a mineral form of hydrous iron(II) sulfate: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite. It alters to siderotil by Dehydration, loss of water. It is a secondary sulfate mineral which forms from the oxida ...

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 aggregate of crystals. The habit of a crystal is dependent on its crystallographic form and growth conditions, which generally creates irregularities d ...

, 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
Pentahydrate minerals 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