West Mine, Bayan Obo deposit, Bayan Obo, Bayan Obo mining district, Baotou City (Baotou Prefecture), Inner Mongolia, Chinai

Regional Level Types
West Mine	Mine
Bayan Obo deposit	Deposit (Active)
Bayan Obo	Town
Bayan Obo mining district	Mining District
Baotou City (Baotou Prefecture)	Prefecture-level City
Inner Mongolia	Autonomous Region
China	Country

The West Orebody is divided into 11 main iron orebodies: eight in Dolts and three in dolomites and surrounding alteration-derived mica slates.

These iron orebodies are numbered I (I1, I2), II, III (III1, III2), IV, V (V1, V2), VI (VI1, VI2), VII VIII, IX, X, and XI. Among them, Nos. I, II, III, IV, V, and VI orebodies contribute to 95.6% of the total ore reserves. Moreover, the Nos. I, III, IV, and V orebodies are large-scale with reserves exceeding 100 Mt each. Together with 102 affiliated orebodies, the West Orebody possesses 113 iron orebodies in total. The orebodies are concentrated in the central region between the Nos. 16 and 48 exploration lines, exhibiting large scales and a maximum depth of 855 m (along the No. 40 exploration line).

The orebodies in the western region (west of the No. 16 exploration line) have shallow depths.

On the other hand, the orebodies in the eastern region (east of the No. 48 exploration line) manifest small thicknesses, scales, and extension bodies. The Nos. V and III orebodies serve as the largest in this area, hosting 58.6% of the total iron ore reserves.

The REE orebodies in the West Orebody are extensive, but they exhibit lower grades (mostly between 1%–2%) compared to those in the Main and East Orebodies. The REE mineralization presents large-scale and overall mineralization, being divided into multi-layer orebodies by iron orebodies. Consequently, the REE orebodies diverge at sites with strong iron mineralization and converge at sites with weak iron mineralization.

There are a total of 62 REE orebodies in the West Orebody. Among them, Nos. R4, R7, R36, and R59 host 94.75% of the total reserves, with the largest REE orebodies — R4 and R7 — accounting for 60.24% of the total reserves. The REE orebodies gradually expand from west to east, first diverging and then converging, and those in the south gradually diminish.

Niobium mineralization is widespread in the West Orebody, forming four niobium-bearing horizons with varying shapes: (1) niobium orebodies within dolomites and slates in the upper part of Dolts; (2) niobium orebodies in the lower part of Dolts; (3) niobium orebodies in the upper part of Dolts, and (4) niobium orebodies within dolomites and slates in the H9 stratum. They are mostly lentoid or stratoid in shape, with attitudes consistent with those of the iron orebodies and showing a parallel distribution. A total of 362 isolated niobium orebodies are concentrated between the Nos. 16 and 48 exploration lines, mainly consisting of single-drilling-controlled lens-like formations. The largest orebody within the West Orebody is the No. 254 orebody extending over a distance exceeding 1 km, hosting 23.4% of all known niobium reserves.

Other Regions, Features and Areas containing this locality

References