Xikuangshan mine () in

Lengshuijiang Lengshuijiang () is a county-level city in Hunan Province, China, it is under the administration of Loudi prefecture-level City. Located in central Hunan, the city is bordered to the north and west by Xinhua County, to the south by Xinshao County ...

Hunan Hunan (, ; ) is a landlocked province of the People's Republic of China, part of the South Central China region. Located in the middle reaches of the Yangtze watershed, it borders the province-level divisions of Hubei to the north, Jiangxi to ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, contains the world's largest deposit of

antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient time ...

. It is unique in that there is a large deposit of

stibnite Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2 S3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony. The name is derived from the ...

(Sb₂S₃) in a layer of

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

. There are three mineral beds which are between 2.5 and 8 m thick which are folded in an

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

that plunges to the south-west. The total mineralised area of the mine has a surface extent of 14 km². There are two different units at the mine, the northern one produces mixed oxide and sulfide such as

stibiconite Stibiconite is an antimony oxide mineral with formula: Sb3O6(OH). Its name originates from Greek "stibi" (antimony) and "konis" (powder), alluding to its composition and habit. It is a member of the pyrochlore super group. Discovery and occurren ...

(Sb₃O₆(OH)) and the southern one produces stibnite.

Ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...

is concentrated and refined on site in a refinery with a capacity of 10,000 tonnes of antimony per year.

History

The mine is thought to have been discovered in 1521 and was originally mined for its

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

deposits. 464,000 tonnes of antimony were produced at the mine between 1892 and 1929. From 1949 to 1981, 172,000 tonnes of antimony were produced. In 1981 1,700 tonnes of ore was being mined each day which was between 2 and 3 percent pure antimony.

Reserves

In 1981, reserves at the Xikuangshan deposit amounted to 10,000,000 tonnes of ore that contained 2 to 3 percent antimony (200-300,000 tonnes of antimony), at the time geologists thought that there may be more in the area. By 2002 the estimated size of the deposit was 2,110,000 tonnes of pure antimony. The ore is composed of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, stibnite and some

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...

Formation

Using

samarium–neodymium dating Samarium–neodymium dating is a radiometric dating method useful for determining the ages of rocks and meteorites, based on the alpha decay of the long-lived samarium isotope () to the stable radiogenic neodymium isotope (). Neodymium isotope rati ...

, it has been estimated that the deposit formed during the late

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

– early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period (around 145 million years ago).

Water Pollution

In April 2010 it was reported that antimony levels in water near the mine were as high as 11 parts per million, a thousand times those found in uncontaminated water. The antimony was found to be in the V oxidation state, believed to be the least dangerous aqueous form (antimony can have a I, III or V oxidation state). The environmental effects of this high level of the rare metal are poorly understood and are currently under investigation by a team from the Chinese Academy of Sciences, Indiana University Bloomington and the University of Alberta.

References

External links

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_crystal_from_Xikuangshan_mine.html" ;"title="stibnite">Photograph of a ~1 m stibnite">Photograph_of_a_~1_m_stibnite
_crystal_from_Xikuangshan_mine(dead_link_24_March_2019)
Report_of_high_antimony_V_in_water_near_the_mineMine_location_Google_Maps
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crystal from Xikuangshan mine">stibnite">Photograph of a ~1 m stibnite
crystal from Xikuangshan mine(dead link 24 March 2019)
Report of high antimony V in water near the mineMine location Google Maps
{{coord missing">Hunan Antimony mines Lengshuijiang Mines in China