2. non-metallic minerals are minerals that are not heat-conductive transparent brittle fracture characteristics of easy fotfet full on Wright. Salt, sulfur, potassium, calcium, Earth, stone, white, etc. l.
2. แร่อโลหะ) is a mineral that is a heat conductor a translucent brittle break easily, including the fluoride / phosphate, rocks, sand, salt, sulfur, potassium Calcium kaolin etc L.