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one of the world’s biggest mercury deposits, in the northern foothills of the Sierra Morena, in the Ciudad Real Province of New Castile in Spain. Until the tenth century the deposit was mined in order to obtain cinnabar paint; later Almadén became one of the world’s major mercury suppliers. At present the extraction of the metal reaches 1,500 -2,000 tons a year, about 40 percent of the world total. The total mercury extraction for all the time the deposit has been exploited is estimated at 250,000 tons. The mercury content in the ore dropped from 10 percent in the early period of the exploitation of the deposit to 5–6 percent in the mid-20th century.

The deposit is composed of Lower Paleozoic shales, sandstones, and quartz, compressed into steep folds and broken folds. Some folds are filled with diabasic and quartz porphyries of the Cenozoic age; these porphyries are thought to be at the origin of the deposit. Ore is found in a band 20 km in length; these are linked with quartz seams forming three parallel ore deposits. Some of the ore beds are 300 -500 m long, with a thickness of 3–12 m, and the mines run as deep as 500 m. The ore consists of fine-grained quartz and cinnabar, with admixtures of pyrite, sericite, calcite, dolomite, barytes, zeolites, and bitumens. Almadén is a hydrothermal deposit; the ore is formed through sedimentation from hot mineral water solutions filtered through seams of cracked quartzite.


Park, C. F., and R. A. MacDiarmid. Rudnye mestorozhdeniia. Moscow, 1966. (Translated from English.)


References in periodicals archive ?
En el presente estudio, el objetivo es documentar la evolucion eco-sostenible de Almaden y su relacion con la mineria del mercurio, para lo cual es necesario un adecuado estudio del territorio circundante, ademas de conocer el comportamiento del mercurio en el medioambiente.
The announcement of the plant and training facility was made following the signing of a deal by the DSO Authority (DSOA) and Chang Whou Almaden.
Almaden, one of the world's largest producers of photovoltaic anti-reflective coated glass, is setting up the plant at DSOA's tech park.
Alzarooni said: "We welcome Chang Zhou Almaden to the hi-tech park and look forward to a symbiotic partnership with the world's largest producer of anti-reflective glass.
The agreement was signed by Dr Mohammad Alzarooni, vice-chairman and chief executive officer of the DSOA; and Jinxi Lin, chairman of Chang Zhou Almaden, during Gitex Technology Week.
Almaden added that the contestants' backstories will also be showcased.
TSX:GGA), a Canadian-based gold producer, has signed a contract with Almaden Minerals Ltd.
Poliquin, said, 'We at Almaden are pleased with the work being conducted by our partner and are very encouraged by the new results.
But just up Cienega Road from old Almaden, Josh Jensen has been making great wine for more than 30 years--Pinot Noirs that have earned his Calera Wine Company the highest respect from Pinot producers the world over.
20, scientists from IBM Almaden Research Center in San Jose, Calif.
Smith, a retired researcher at the IBM Almaden Research Center who died in 1999 at age 79, is being honored for his pioneering studies of the basic engineering properties of elastomers and glassy polymers.