Perite is a mineral that has a general chemical formula of
Pb Bi O2 Cl.
The name is given for
Per Adolf Geijer, a
Swedish
Swedish or ' may refer to:
Anything from or related to Sweden, a country in Northern Europe. Or, specifically:
* Swedish language, a North Germanic language spoken primarily in Sweden and Finland
** Swedish alphabet, the official alphabet used by ...
economic
geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
with the
Geological Survey of Sweden, who discovered the mineral in 1960 outside of
Langban,
Sweden
Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
.
[ Perite is ]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 ...
, space group Cmcm . In terms of its optical properties, Perite is anisotropic
Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...
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
Pleochroism (from Greek πλέων, ''pléōn'', "more" and χρῶμα, ''khrôma'', "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light.
Backgroun ...
. Perite is found in areas near igneous
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...
extrusions in places like the Western United States, Southern Australia, and scattered around Europe.
Crystallography
Perite belongs to the Orthorhombic crystal system, and has the properties of 2/m 2/m 2/m crystal class. Therefore, perite has 3 mirror planes and 3 twofold rotation axes.
References
Bismuth minerals
Halide minerals
Lead minerals
Orthorhombic minerals
Minerals in space group 63
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