Eveite
Encyclopedia
Eveite is a manganese
arsenate mineral
in the olivenite
group. Its chemical formula is Mn2AsO4OH. It is found only in Långban
, Filipstad
, Värmland
, Sweden
and at the Sterling Mine in New Jersey
, United States of America. It is a dimorph
of sarkinite and is isostructural with adamite
. The name, for the biblical "Eve", comes from its structural similarities to adamite and is also a reference to its apple-green color. It can also be pale yellow. Eveite is an orthorhombic mineral, which means it has three crystallographic axes of unequal lengths which are at 90° to one another.
Eveite is anisotropic, which means that its physical and optical properties differ with respect to direction. It has high relief, which is the apparent topography exhibited by minerals in thin section as a consequence of refractive index. It is biaxial, so it has two optic axes and three indices of refraction
n depending on the crystallographic direction. The refractive index is the ratio of the velocity of light in a vacuum to that in the mineral. The difference between the highest and lowest indices of refraction is called the birefringence, so the birefringence of eveite is β = .032.
Eveite is significant because it was the first mineral to show Mn2+ atoms in five-fold coordination, which is otherwise undocumented in mineral structures. It's an important addition to the olivenite group, and isostructural with andalusite
. Because it shows up in very small quantities and in only two locations, it has no commercial use. It is relatively low-density and is associated with high hydrate and low density arsenates in open cavities, which contributes to its rarity.
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...
arsenate mineral
Arsenate mineral
Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the 3- anion group and, more rarely, other arsenates with anions like AsO32- or [AsO22]- . Arsenite minerals are much less common...
in the olivenite
Olivenite
Olivenite is a copper arsenate mineral, formula Cu2AsO4OH. It crystallizes in the monoclinic system , and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces...
group. Its chemical formula is Mn2AsO4OH. It is found only in Långban
Långban
Långban is a mining area in Värmland in Sweden. It belongs to Filipstad Municipality, with the nearest city being Filipstad, 21 km south. It was systematically mined through 1711-1972, but has traces from the 15th century. It is the birthplace of Swedish-American inventor John EricssonIt has...
, Filipstad
Filipstad
Filipstad is a locality and the seat of Filipstad Municipality, Värmland County, Sweden with 6,177 inhabitants in 2005.Filipstad was granted city privileges in 1611 by Charles IX of Sweden, who named it after his son Duke Carl Philip .After a major fire destroyed forest and town in 1694, Filipstad...
, Värmland
Värmland
' is a historical province or landskap in the west of middle Sweden. It borders Västergötland, Dalsland, Dalarna, Västmanland and Närke. It is also bounded by Norway in the west. Latin name versions are Vermelandia and Wermelandia. Although the province's land originally was Götaland, the...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
and at the Sterling Mine in New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, United States of America. It is a dimorph
Polymorphism (materials science)
Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...
of sarkinite and is isostructural with adamite
Adamite
Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with...
. The name, for the biblical "Eve", comes from its structural similarities to adamite and is also a reference to its apple-green color. It can also be pale yellow. Eveite is an orthorhombic mineral, which means it has three crystallographic axes of unequal lengths which are at 90° to one another.
Eveite is anisotropic, which means that its physical and optical properties differ with respect to direction. It has high relief, which is the apparent topography exhibited by minerals in thin section as a consequence of refractive index. It is biaxial, so it has two optic axes and three indices of refraction
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
n depending on the crystallographic direction. The refractive index is the ratio of the velocity of light in a vacuum to that in the mineral. The difference between the highest and lowest indices of refraction is called the birefringence, so the birefringence of eveite is β = .032.
Eveite is significant because it was the first mineral to show Mn2+ atoms in five-fold coordination, which is otherwise undocumented in mineral structures. It's an important addition to the olivenite group, and isostructural with andalusite
Andalusite
Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5.The variety chiastolite commonly contains dark inclusions of carbon or clay which form a checker-board pattern when shown in cross-section....
. Because it shows up in very small quantities and in only two locations, it has no commercial use. It is relatively low-density and is associated with high hydrate and low density arsenates in open cavities, which contributes to its rarity.