Wakabayashilite is a rare

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...

antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient t ...

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, th ...

with formula .Bonazzi, P., Lampronti, G. I., Bindi, L. and Zanardi, S. (2005) Wakabayashilite,: Crystal structure, pseudosymmetry, twinning and revised chemical formula. American Mineralogist, 90, 1108–1114.

Discovery and occurrence

Wakabayashilite is a rare mineral first discovered in Nevada in the 1920s, but it was mistaken for a hair orpiment.Gibbs, R.B. (1985) The White Caps Mine, Manhattan. ''Nevada: Mineralogical Record'', 16, 81-88. In the 1970s, wakabayashilite was found in Japan and scientifically identified as a new mineral. It was named after Yaichiro Wakabayashi (1874–1943), a Japanese mineralogist of the Mitsubishi Mining Company in Japan. Wakabayashilite has been discovered later in several places around the world such as in Saha Republic (Russia), Zhuang region (China) and Hautes-Alpes (France). In the United States, Wakabayashilite has been found at the White Caps Mine, in the Toquima Range of mountains, Nye County, Nevada. Other Nevada locations where the mineral has been found include the Getchel Mine, in the Osgood Mountains, Humboldt County, and at the Seminole-Regent Mine, in the Rawhide Mining District, Mineral County. Originally, Wakabayashilite was found in druses of quartz associated with

orpiment Orpiment is a deep-colored, orange-yellow arsenic sulfide mineral with formula . It is found in volcanic fumaroles, low-temperature hydrothermal veins, and hot springs and is formed both by sublimation and as a byproduct of the decay of anothe ...

and

realgar Realgar ( ), also known as "ruby sulphur" or "ruby of arsenic", is an arsenic sulfide mineral with the chemical formula α-. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in asso ...

, however, it was later found embedded in calcite as well. Generally, it mostly occurs with other arsenic minerals in high-arsenic gold deposits.

Structure and optical properties

Even though Wakabayashilite possesses the hexagonal pseudosymmetry, it actually belongs to the orthorhombic

crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices. Space groups are classified into crystal systems according to their poin ...

meaning it contains three axes of different length but are mutually perpendicular to one another.Klein, C., and Dutrow, B. (2007) The 23rd edition of the Manual of Mineral Science, 130. John Wiley and Sons, Inc. Hoboken, New Jersey, U.S.A. It also belongs to the

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 uncha ...

Pna2₁. For its optical properties, Wakabayashilite is a biaxial mineral and its color in plane polarized light is golden-yellow to lemon-yellow and it also has strong pleochroism. For now, since wakabayashilite is rare, it is of no obvious economical interest. However, there have been some recent research conducted on its interesting structure, pseudosymmetry and twinning.

References

{{Reflist Sulfide minerals Arsenic minerals Antimony minerals Orthorhombic minerals Minerals in space group 33