Eveite is a

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

arsenate mineral Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the (AsO4)3− anion group and, more rarely, other arsenates with anions like AsO3(OH)2− (also written HAsO42−) (example: pharmacolite Ca(AsO3OH).2H2O) or ( ...

in the

olivenite Olivenite is a copper arsenate mineral, formula Cu2 As O4O H. It crystallizes in the monoclinic system (pseudo-orthorhombic), and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces. More commonl ...

group. Its chemical formula is Mn₂AsO₄OH. It is found only in

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 birthp ...

Filipstad Filipstad is a locality and the seat of Filipstad Municipality, Värmland County, Sweden, with 10,644 inhabitants in 2019. Filipstad was granted city privileges in 1611 by Charles IX of Sweden, who named it after his son Duke Carl Philip (1601&n ...

Värmland Värmland () also known as Wermeland, is a '' landskap'' (historical province) in west-central Sweden. It borders Västergötland, Dalsland, Dalarna, Västmanland, and Närke, and is bounded by Norway in the west. Latin name versions are '' ...

, Sweden and at the Sterling Mine in

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

, United States. 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 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'' = 0.032. 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 is therefore an important addition to the olivenite group. 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.

References

{{Reflist * Pabst, A. (1970) New Mineral Names. American Mineralogist, 55, 319-320. * Moore, P. and Smyth, J. (1968) Crystal Chemistry of the Basic Manganese Arsenates: III. The Crystal Structure of Eveite. American Mineralogist, 53, 1841-1845. * Moore, P. (1968) Eveite, Mn₂²⁺AsO₄OH, a new mineral from Långban. Arkiv För Mineralogi Och Geologi, 4.26, 473-476. Arsenate minerals Manganese(II) minerals Orthorhombic minerals Minerals in space group 58