Chalcanthite
Encyclopedia
Chalcanthite, whose name derives from the Greek, chalkos and anthos, meaning copper flower, 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.
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.
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 crystal
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.
, blue vitriol, and copper vitriol.
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
CuSO4·5H2O. It is commonly found in the late-stage oxidation zones of copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
deposits. Due to its ready solubility, chalcanthite is more common in arid regions.
Chalcanthite is a pentahydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
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
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
by either manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
as jokokuite, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
as siderotil
Siderotil
Siderotil is an iron sulfate hydrate mineral with formula: FeSO4·5H2O which forms by the dehydration of melanterite. Copper commonly occurs substituting for iron in the structure. It typically occurs as fibrous or powdery encrustations, but may also occur as acicular triclinic crystals.It was...
, or magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
as pentahydrite.
Uses of chalcanthite
As chalcanthite is a copper mineral, it can be used as an oreOre
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
of copper. However, its ready solubility in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
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
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
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- CalciteCalciteCalcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
and its polymorphAllotropyAllotropy or allotropism is the property of some chemical elements to exist in two or more different forms, known as allotropes of these elements...
, aragoniteAragoniteAragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
, both CaCalciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust... - BrochantiteBrochantiteBrochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is CuSO4·3Cu2. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it is named for its discoverer, the French geologist and mineralogist, A. J. M...
, CuCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
46 - ChalcopyriteChalcopyriteChalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
, CuCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
FeIronIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
SSulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
2 - MalachiteMalachiteMalachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
, CuCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
22 - MelanteriteMelanteriteMelanterite is a mineral form of hydrous iron sulfate: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite. It alters to siderotil by loss of water. It is a secondary sulfate mineral which forms from the oxidation of primary sulfide minerals such as pyrite and marcasite in the...
, FeIronIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
Alternative names
Chalcanthite has several alternative names, including blue stoneBlue stone
Blue stone is a generic mineral description commonly applied to a variety of minerals. Perhaps the most common reference is to the hydrated copper sulfate mineral, chalcanthite. The name "blue stone" is also applicable to lazurite, the core constituent of lapis lazuli, a sulfide of sodium aluminium...
, blue vitriol, and copper vitriol.