The Clara Pit () or Clara Mine is a working mine in

Oberwolfach Oberwolfach () is a town in the district of Ortenau (district), Ortenau in Baden-Württemberg, Germany. It is the site of the Oberwolfach Research Institute for Mathematics, or Mathematisches Forschungsinstitut Oberwolfach. Geography Geograph ...

in the

Black Forest The Black Forest ( ) is a large forested mountain range in the States of Germany, 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 th ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

in which the industrial minerals,

baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate (Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

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 substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

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 (e.g. in welding electrodes) in the glass and ceramics industry and in the chemical industry for the production of

hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling p ...

. 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 or '' Azure spar'Krivovichev V. G.'' Mineralogical glossary. Scientific editor A. G. Bulakh. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0. ''(in Russian)'' is a soft, deep-blue copp ...

, chrysocolla, claraite, cornwallite,

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 scal ...

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,

copper Copper is a chemical element; it has symbol Cu (from Latin ) 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 pinkish-orang ...

malachite Malachite () is a copper Carbonate mineral, carbonate hydroxide mineral, with the chemical formula, formula Basic copper carbonate, Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often for ...

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 ...

, pyromorphite,

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

stolzite Stolzite is a mineral, a lead tungstate; with the chemical formula, formula Pbtungsten, Woxygen, O4. It is similar to, and often associated with, wulfenite which is the same chemical formula except that the tungsten is replaced by molybdenum. Stol ...

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

und scorodite.

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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