Perite
Encyclopedia
Perite has a general chemical formula of Pb
Bi
O
2Cl
. The name is given for its founder Per Adolf Geijer, a Swedish economic geologist
with the Geological Survey of Sweden
, who discovered the mineral in 1960 outside of Langban
, Sweden
. Perite is orthorhombic, which means crystallographically
, it contains three axes of two of equal length (the bases a and b) and one of a little longer or shorter length. All three bases intersect at a 90° angles. It belongs to the space group
Cmcm {C2/m 2/c 21/m}. In terms of its optical properties, Perite is anisotropic which means the velocity of light varies depending on direction through the mineral (i.e. it is birefringent). Its calculated relief is 1.45-1.461, which is moderate. It is colorless in plane polarized light, and it is weakly pleochroic. Perite is found in areas near igneous extrusions in places like the Western United States, Southern Australia, and scattered around Europe.
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
Bi
Bismuth
Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent poor metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
2Cl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
. The name is given for its founder Per Adolf Geijer, a Swedish economic geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
with the Geological Survey of Sweden
Geological Survey of Sweden
Geological Survey of Sweden is a Swedish government agency that was founded in 1858 dealing with questions about the nature of the geological and mineral management in Sweden....
, who discovered the mineral in 1960 outside of Langban
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...
, 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....
. Perite is orthorhombic, which means crystallographically
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
, it contains three axes of two of equal length (the bases a and b) and one of a little longer or shorter length. All three bases intersect at a 90° angles. It belongs to the space group
Space group
In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...
Cmcm {C2/m 2/c 21/m}. In terms of its optical properties, Perite is anisotropic which means the velocity of light varies depending on direction through the mineral (i.e. it is birefringent). Its calculated relief is 1.45-1.461, which is moderate. It is colorless in plane polarized light, and it is weakly pleochroic. Perite is found in areas near igneous extrusions in places like the Western United States, Southern Australia, and scattered around Europe.