Bayan'obo Mining District ( Mongolian: , zh, s=白云鄂博矿区), or Baiyun-Obo or Baiyun'ebo, is a mining

district A district is a type of administrative division that in some countries is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or county, counties, several municipality, municip ...

in the west of

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an Autonomous regions of China, autonomous region of China. Its border includes two-thirds of the length of China's China–Mongolia border, border with the country of Mongolia. ...

, China. It is under the administration of

Baotou Baotou; is the largest city by urban population in Inner Mongolia, China. Governed as a prefecture-level city, as of the 2020 census, its built-up (''or metro'') area made up of its 5 urban districts is home to 2,261,089 people with a total po ...

City, the downtown of which is more than to the south. The mines north of the town are the largest deposits of

rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...

s yet found and, as of 2005, responsible for 45% of global rare-earth element production. In the satellite image at right, vegetation appears red, grassland is light brown, rocks are black, and water surfaces are green. Two circular open-pit mines are visible, as well as a number of tailings ponds and tailings piles.NASA Bayan Obo image and writeup
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Administrative divisions

Bayan Obo Mining District is made up of 2 subdistricts.

Climate

Economic geology

China produced about 81,000 tons of rare-earth metals in 2001; the number jumped to about 120,000 by 2006. According to the Chinese Society of Rare Earths, of waste gas—containing dust concentrate, hydrofluoric acid, sulfur dioxide, and sulfuric acid—are released with every ton of rare metals that are mined. Approximately of acidic wastewater, plus about a ton of radioactive waste residue are also produced.

Mine deposit

Very large rare-earth elements (REE) Fe-Nb deposit (Bayan-Obo type), discovered as an iron deposit in 1927. REE minerals were discovered in 1936, and

niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

-bearing ores in the late 1950s. Reserves are estimated at more than 40 million tons of REE minerals grading at 3–5.4% REE (70% of world's known REE reserves), 1 million tons of Nb₂O₅ and 470 million tons of iron. The deposit also contains an estimated 130 million tons of

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 ...

. Bayan'obo is the world's largest known REE deposit. The fluorite content of the ores also makes it the world's largest fluorite deposit. The deposit occurs in an east–west trending

Mesoproterozoic The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic ...

rift zone along the northern margin of the Sino-Korean Craton. Host strata are quartzite, slate, limestone, and dolomite. Dolomite is the main host rock. The orebodies are stratiform and lenticular, with masses, bands, layers, veins, and disseminations. Besides clear features of

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

mineralization, the deposit also exhibits Mg, Fe, Na and F

metasomatism Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in the chemical com ...

. Sm-Nd monazite isochron age for bastnaesite and

riebeckite Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long ...

is 1200 to 1300 Ma, whereas Th-Pb and Sm-Nd age of Ba-REE-F carbonates and aeschynite is 474 to 402 Ma. at

Mindat.org Mindat.org is a non-commercial interactive online database covering minerals around the world. Originally created by Jolyon Ralph as a private project in 1993, it was launched as a community-editable website in October 2000. it is operated by ...

Administrative divisions

Climate

Economic geology

Mine deposit

See also

References

Further reading