copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
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 the chemical formula Cu8S5. The mineral is named after the original collector, Adam Geer, of
Utica, New York
Utica () is a city in the Mohawk Valley and the county seat of Oneida County, New York, United States. The tenth-most-populous city in New York State, its population was 65,283 in the 2020 U.S. Census. Located on the Mohawk River at the ...
, US.
Crystallography
Geerite is in the crystal class . This means that the crystal could be inverted and then rotated by 120 degrees to return to its original position. The optical class of geerite is unknown. Geerite is anisotropic which means that it will show interference colors when it is rotated in cross polarized light and that the mineral has different properties in different directions
Discovery and occurrence
It was first described in 1980 for an occurrence as thin coatings or platelets replacing sphalerite in the type locality in De Kalb Township,
Saint Lawrence County, New York
St. Lawrence County is a county in the U.S. state of New York. As of the 2020 census, the population was 108,505.
The county seat is Canton.
The county is named for the Saint Lawrence River, which in turn was named for the Christian saint La ...
. It also occurs in a
magnetite
Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With th ...
serpentinite
Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''se ...
-hosted deposit in
Eretria
Eretria (; el, Ερέτρια, , grc, Ἐρέτρια, , literally 'city of the rowers') is a town in Euboea, Greece, facing the coast of Attica across the narrow South Euboean Gulf. It was an important Greek polis in the 6th and 5th centur ...
,
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...
. It occurs associated with spionkopite, sphalerite,
tetrahedrite
Tetrahedrite is a copper antimony sulfosalt mineral with formula: . It is the antimony endmember of the continuous solid solution series with arsenic-bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the two, ...
,
chalcopyrite
Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mo ...
,
malachite
Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fracture ...
,
azurite
Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a basic carb ...
,
brochantite
Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is Cu4SO4(OH)6. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it was named by Armand Lévy for his fellow Frenchman, geologist ...
,
chrysocolla
Chrysocolla ( ) is a hydrated copper phyllosilicate mineral and mineraloid with formula (x<1) or .
The structure of the mineral has been questioned, as a 2006 spectrographic study suggest material identified as ...
hemimorphite
Hemimorphite is the chemical compound Zn4( Si2O7)( OH)2 ·H2O, a component of mineral calamine. It is a silicate mineral which, together with smithsonite (ZnCO3), has been historically mined from the upper parts of zinc and lead ores. Both ...
and calcite in the type locality; and with spionkopite, chalcopyrite,
cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...
ian
pentlandite
Pentlandite is an iron–nickel sulfide with the chemical formula . Pentlandite has a narrow variation range in Ni:Fe but it is usually described as having a Ni:Fe of 1:1. It also contains minor cobalt, usually at low levels as a fraction of wei ...
,
magnetite
Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With th ...
andradite
Andradite is a mineral species of the garnet group. It is a nesosilicate, with formula Ca3Fe2Si3O12.
Andradite includes three varieties:
* ''Melanite'': Black in color, referred to as "titanian andradite".chlorite,
diopside
Diopside is a monoclinic pyroxene mineral with composition . It forms complete solid solution series with hedenbergite () and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull ...
in the Eretria deposit.
It has also been reported from a variety of locations worldwide, including the Logatchev-1 hydrothermal field along the
Mid-Atlantic Ridge
The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North ...
complex.
It has been used to study crystal structure and bonding in copper sulfides.
See also
*
Copper sulfide
Copper sulfides describe a family of chemical compounds and minerals with the formula CuxSy. Both minerals and synthetic materials comprise these compounds. Some copper sulfides are economically important ores.
Prominent copper sulfide mineral ...