The Clara Pit (german: Grube Clara) or Clara Mine is a working

mine Mine, mines, miners or mining may refer to: Extraction or digging * Miner, a person engaged in mining or digging *Mining, extraction of mineral resources from the ground through a mine Grammar *Mine, a first-person English possessive pronoun ...

Oberwolfach Oberwolfach ( gsw, label= Low Alemannic, Obberwolfä) is a town in the district of Ortenau in Baden-Württemberg, Germany. It is the site of the Oberwolfach Research Institute for Mathematics, or Mathematisches Forschungsinstitut Oberwolfach. Ge ...

in the

Black Forest The Black Forest (german: Schwarzwald ) is a large forested mountain range in the state of Baden-Württemberg in southwest Germany, bounded by the Rhine Valley to the west and south and close to the borders with France and Switzerland. It is t ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

in which the industrial minerals, baryte and fluorspar are mined.

Importance

The pit is well known because, to date, over 375 different

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

s have been found here (as at November 2004), including several that are very rare. The portal of the mine is located in the upper part of the Rankach valley. The processing plant is near Wolfach-Kirnbach in the Kinzig valley. Since 1898, the Clara Pit has mined over 3 million tonnes of baryte and over 2 million tonnes of fluorspar. Baryte is used ''inter alia'' in sound attenuation, radiation protection and the deep mining industry. Fluorspar or fluorite is used in the metal industry as a

plasticiser A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticize ...

(e.g. in welding electrodes) in the glass and ceramics industry and in the chemical industry for the production of hydrofluoric acid. The pit, which is operated by the firm of Sachtleben Bergbau is the last active mine of the many that were once worked in the Black Forest. Its most common minerals are

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 ...

, baryte,

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 ...

, claraite,

cornwallite Cornwallite is an uncommon copper arsenate mineral with formula Cu5(AsO4)2(OH)4. It forms a series with the phosphate pseudomalachite and is a dimorph of the triclinic cornubite. It is a green monoclinic mineral which forms as radial to fibrous ...

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...

clinoclase Clinoclase is a hydrous copper arsenate mineral, Cu3AsO4(OH)3. Clinoclase is a rare secondary copper mineral and forms acicular crystals in the fractured weathered zone above copper sulfide deposits. It occurs in vitreous, translucent dark blue to ...

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 ...

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 ...

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

pyromorphite Pyromorphite is a mineral species composed of lead chlorophosphate: Pb5( P O4)3 Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal pl ...

mimetite Mimetite is a lead arsenate chloride mineral (Pb5(AsO4)3Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name derives from the Greek Μιμητής ''mimetes'', meaning "imitator" a ...

, stolzite,

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

und

scorodite Scorodite is a common hydrated iron arsenate mineral, with the chemical formula FeAsO4·2H2O. It is found in hydrothermal deposits and as a secondary mineral in gossans worldwide. Scorodite weathers to limonite. Scorodite was discovered in the ...

Mineral tailings

On the mineral tailings site of the Clara Pit in Wolfach-Kirnbach the various minerals may be looked for in separate raw mineral ore spoil heaps.

Museum

In the Oberwolfach Mining and Mineral Museum in the village of Kirche over 200 minerals from the pit are displayed.

Geology

The fissures in the mine are part of the Friedrich Christian Herrensegen Fault Zone in the Black Forest Gneiss Complex.

Type localities

The Clara Pit has given its name to the mineral, claraite and is also the type locality for the following minerals: agardite-(Ce), arsenbrackebuschite, arsenocrandallite, arsenogorceixite, arsenogoyazite, bariopharmacosiderite, benauite, bismutostibiconite, claraite, cualstibite, phosphofibrite, phyllotungstite, rankachite, rhabdophane-(Ce), tungstibite, uranotungstite.''Uranotungstite''
at mindat.org. Retrieved 13 Apr 2017.

References

External links

Grube Clara at Mineralienatlas.deOberwolfach Mining and Mineral MuseumGrube Clara at Clara-Mineralien.de
Information on the pit, minerals and geology

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