What is the content of rare earth in the mud?

The content of rare earth in mud is 190mg/kg. General situation of soil rare earth elements in China, according to the analysis results of soil samples in China 1 187, the total content of rare earth elements in soil is 190mg/kg, and the range is 18 ~ 582 mg/kg. Rare earth is the general name of 17 metal elements in the periodic table, including lanthanides, scandium and yttrium. There are 250 kinds of rare earth minerals in nature. Finnish chemist JohnGadolin was the first person to discover rare earths. 1794, he separated the first rare earth "element" (yttrium soil, that is, Y2O3) from a heavy ore shaped like asphalt.