The abundance of chromium in the earth's crust is 0.035%, but the chromium ore produced is high in chromium. The chromite resources in the nearly north-south fold belt on the earth account for more than 95% of the world's total, of which the chromium resources of the Precambrian fold belt running through eastern Africa account for 94% of the world's total. The Ural Wallisi fold belt accounts for about 2%, and the Alpine fold belt accounts for about 2% of the world's total. The chromium ore-forming geological conditions in China are not ideal, and the north-south chromite belt has not been found in the Cambrian geological area.
Tibet-Yunnan chromite deposits belong to the Alpine fold zone; Xinjiang-Gansu and Qinghai-Inner Mongolia chromite deposits are in the east-west fold zone in the Hercynian period; they do not have the conditions to produce very large deposits. The main chromium-bearing mineral with industrial value is chromium spinel, which is often mistakenly called chromite. There are three most useful chromium spinel minerals: magnesia chromite (Mg, Fe) Cr2O4, hard chromium spinel (Mg, Fe) (Cr, Al) 2O4 and aluminochromite Fe (Cr, Al) 2O4.
