Nws yog siv rau kev tshem tawm cov hlau thiab purification ntawm cov hlau tsis muaj hlau hauv kev ntub dej, tshwj xeeb tshaj yog rau cov hlau ntub dej tshem tawm cov hlau tsis muaj hlau xws li quartz xuab zeb, potassium feldspar, thiab dej qab zib feldspar. Tsis tas li ntawd, nws muaj kev sib cais zoo rau cov tsis muaj zog. Cov khoom siv hlau nplaum xws li hematite, limonite, specularite, siderite, manganese ore, thiab tantalum-niobium ore.