Colimaite, the naturally occurring analog of synthetic K₃VS₄, is a

sulfide mineral The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the ...

discovered in southwestern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

vanadium Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer ( pas ...

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

was collected from the crater of the Colima volcano. The mineral colimaite is named after the locality of this volcanoOstrooumov, M., Taran, Y., Arellano-Jimenez, M., Ponse, A., and Reyes-Gasga, J. (2009) Colimaite, K3VS4 – anew potassium-vanadium sulfide mineral from the Colima volcano, State of Colima (Mexico)

Revista Mexicana de Ciencias Geológicas The ''Revista Mexicana de Ciencias Geológicas'' is a triannual peer-reviewed open-access scientific journal published by the National Autonomous University of Mexico, Sociedad Geológica Mexicana, Instituto Nacional de Geoquímica, and Socieda ...

, 26(3), 600-608 and has been approved in 2007, along with its mineral name, by the Commission on New Minerals, Nomenclature and Classification (CNMNC). It has been given the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. Th ...

number of IMA 2007–045.

Composition

The chemical formula of colimaite is K₃VS₄. The enrichment of vanadium in Colima's

volcanic gas Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...

es make it unique. The study of

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

content in the

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

s is also important, in order to know how an eruption could affect global climate due to SO₂ emissions.

Structure

Colimaite exhibits the Pnma (P 2₁/n 2₁/m 2₁/a)

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...

making it

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a r ...

. The vanadium and sulfur atoms form tetrahedra. Potassium ions separate these tetrahedra in two different ways. In one case, the potassium ion is bound to five sulfur atoms at an average distance of 3.296 Å with an additional two sulfur atoms at a distance of 3.771 Å. In the other case, the potassium ion is bound to eight sulfur atoms at an average distance of 3.314 Å. In both cases, the potassium ions are in an irregular coordination polyhedron.

Physical properties

The formations of colimaite have been described as

hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introducti ...

–like particles due to the acicular habit of extremely fine needles forming the

aggregate Aggregate or aggregates may refer to: Computing and mathematics * collection of objects that are bound together by a root entity, otherwise known as an aggregate root. The aggregate root guarantees the consistency of changes being made within the ...

s. The size of these aggregates range from 10 to 100 µm. The needles themselves have been measured up to 50 µm in length and 20 µm in width. Although colimaite belongs to the orthorhombic crystal class, their crystallographic forms were not observed. The particles were regular

parallelepipeds In geometry, a parallelepiped is a three-dimensional figure formed by six parallelograms (the term ''rhomboid'' is also sometimes used with this meaning). By analogy, it relates to a parallelogram just as a cube relates to a square. In Euclide ...

and elongated rectangular prisms. The color of colimaite is dark golden and opaque. The streak is a yellow green with a resinous to greasy luster. It is non-fluorescent. It is brittle with no observed cleavage and a splintery fracture. Because of grain size, the hardness and density could not be measured but the density has been calculated to 2.235 g/cm³.

Geological occurrence

Colimaite occurs as a sublimate from the volcanic fumaroles of the Colima volcano in Mexico. Other minerals including

cristobalite Cristobalite is a mineral polymorph of silica that is formed at very high temperatures. It has the same chemical formula as quartz, SiO2, but a distinct crystal structure. Both quartz and cristobalite are polymorphs with all the members of the ...

arcanite Arcanite is a potassium sulfate mineral with formula: K2SO4. Arcanite was first described in 1845 for an occurrence in old pine railroad ties in the Santa Ana tin mine, Trabuco Canyon, Santa Ana Mountains, Orange County, California, US. It has als ...

, thenardite,

baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

and

native gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

have been collected from the fumaroles of this volcano. Although minerals were collected at temperatures from 400 to 800 °C, colimaite was assembled in a more narrow temperature interval of 450 - 600 °C. There are similarities between the volcanic gases of the Colima crater and the gases of other volcanoes,Taran, Y. A., Bernard, A., Gavilanes, J., and Africano, F. (2000) Native gold in mineral precipitates from high-temperature volcanic gases of Colima volcano, Mexico. Applied Geochemistry, 15, 337-346 but there are some differences that make Colima unique. Notable differences are the vanadium,

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

and

copper Copper is a chemical element with the symbol Cu (from la, cuprum) 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 pinkis ...

enrichment of the Colima gases. These same gases also lack

cadmium Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...

and

molybdenum Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lea ...

Special characteristics

Not only is colimaite the first new mineral species discovered in Mexico since 1998, but it is also the first newly recognized mineral species collected from the fumaroles of the Colima volcano crater. It was collected by the use of two

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

tubes of one meter in length each, placed in a high temperature vent at the volcano's crater.

References

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External links

Entry on mindat.orgEntry on webmineral.com
Sulfide minerals Orthorhombic minerals Minerals in space group 62 Vanadium minerals Thiometallates Potassium minerals