They are employed by coal, metal and non-metallicmineral mines and quarries.
他们受雇于煤炭，金属和非金属矿物矿场和采石场。
2
At present, the domestic and international research about the mineral biotechnology concentrates on the metallic ores mainly, and there is much less research in the fields of non-metallic ores.
目前，国内外有关矿物微生物技术的研究主要集中于金属矿，非金属矿方面的研究较少。
3
Kaolin is an important non - metallicmineral resources and it can be used in papermaking, rubber, plastics and so on.