Chalcocite
- Chalcocite
- Copper glass
Chalcocite, outdated also known as chalcocite or copper glass, is a commonly occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the monoclinic crystal system with the composition Cu 2 (also α - Cu2S ), that is chemically a copper (I ) sulfide.
Chalcopyrite is opaque in every shape and usually develops prismatic, tabular and by twinning and pseudo-hexagonal crystals. Furthermore, he finds himself in the form of granular to massive aggregates. Fresh samples are first of lead- gray to steel-gray color and metallic luster. With time, however, they run to black and matte.
Etymology and history
The name of the mineral chalcocite received in 1832 by François Sulpice Beudant, who derived the name from the Greek word Χαλκός [ Chalkos ] for copper.
The mineral was known, however, already in the 16th century under the name of mining copper glass and later as chalcocite.
Classification
Already in the now outdated but still in use 8th edition of the mineral classification by Strunz was one of chalcocite to the mineral class of " sulfides and sulfosalts " and then to the Department of " sulfides with the molar ratio of metal: sulfur, selenium, tellurium > 1: 1" where he collaborated with Anilith, digenite, Djurleit, Geerit, Roxbyit, Spionkopit and Yarrowit the " copper sulfide group " with the system no. II/B.01 formed.
The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the chalcocite also in the class of " sulfides and sulfosalts " and there in the department of "Metal Sulfides, M: S> 1: 1 ( mainly 2: 1) " a. This division, however, is further subdivided according to the conditions prevailing in the interconnect metals, so that the mineral according to its composition in the subdivision " with copper ( Cu), silver (Ag ) and / or gold ( Au) " can be found, where it acts as only member is the unnamed group 2.BA.05a.
The mainly common in English-speaking classification of minerals according to Dana assigns the chalcocite in the class of " sulfides and sulfosalts " and then in the Department of " sulfide minerals ." Here he is with Djurleit, digenite, Roxbyit, Anilith, Geerit and Spionkopit in the eponymous " Chalkosingruppe (formula: Cu2 - xS ) " with the system no. 02:04:07 within the subdivision " sulfides - tellurides and selenides, including - with the composition AmBnXp, with (m n): p = 2: 1" to find.
Education and Locations
As a frequent mineral formation chalcocite is found at many localities that are mainly divided into two types of education:
In speed and displacement deposits, rarely also in pegmatitic - pneumatolytic deposits that are penetrated by ascending ( ascendant ) hydrothermal solution, the chalcocite usually forms in paragenesis with bornite, enargite, various Fahl ore, pyrite and other sulfides. Known deposits of this type include Butte ( Montana) in the USA, Schesqasghan (formerly Džezkazgan ) in Kazakhstan, Tsumeb in Namibia, Musina (formerly Messina) in South Africa and the " Turjinskii Mine" ( Turginsk mine ) on the river in the northern Urals in Turja Russia.
In descending ( the Descendant ) sedimentation and Zementationszonen be enriched chalcocite often at by precipitating copper sulfate-containing solutions, with other sulfides are displaced. Many of these mineral rich Zementationszonen and vein deposits are mainly in Europe and the U.S. since been dismantled and the dismantling of rather poor porphyry copper deposits is often economically feasible only in secondary enrichments. Known reserves include, among others, the Bingham Canyon Mine ( Utah) and Bisbee (Arizona ) in the USA and Cerro de Pasco in Peru. Of great importance are the Kupferschiefer at Mansfeld- Sangerhausen in Germany, the copper marl in the area of Legnica in Poland, Qonyrat are ( Kounrad ) in Kazakhstan, Olmaliq ( Almalyk ) in Uzbekistan and the Central Asian Altai Mountains.
In the oxidation zone, however, chalcocite is not persistent and is either replaced by native copper, by the sulfide covellite, cuprite through the oxide or carbonates azurite and malachite.
Worldwide, chalcocite so far (as of 2012) are detected at around 4500 localities, so among other things, on the Antarctic Peninsula, in rock samples from the Mid-Atlantic Ridge and the East Pacific Rise.
Known due to exceptional Chalkosinfunde also are the " M'Sesa Mine" at Kambove ( Katanga Province ) in the Democratic Republic of Congo, where up to 25 cm large crystals were found. Well -formed crystals with several centimeters in diameter were also in Redruth and St Just (England ) in the United Kingdom, Bristol ( Connecticut ) and in the " Flambeau Mine" in Ladysmith (Wisconsin ) in the United States.
Crystal structure
Chalcopyrite, more low - chalcocite (also low chalcocite ) crystallizes in the monoclinic space group P21 / c ( Raumgruppen-Nr. 14) with the lattice parameters a = 15.25 Å; b = 11.88 Å; c = 13.49 Å and β = 116.3 °, and 48 formula units per unit cell.
At a temperature of about 103 ° C low - chalcocite goes into the hexagonal modification and is accordingly called high - chalcocite or high - chalcocite. The space group of high - chalcocite is P63/mmc ( Raumgruppen-Nr. 194 ), corresponding to the lattice parameters a = 3.95 Å and c = 6.75 Å at 2 formula units per unit cell.
Use
Chalcopyrite was to exhaustion of the richest mining areas in England and the United States an important raw material for the production of copper. Today chalcocite still plays along with other copper sulfides such as bornite and covellite a major role as ore mineral in stratabound deposits such as by Lubin in Lower Silesia, Poland.