Refractive Index 1.58- 1.62Bulk Density (kg/m3) approx. 145 - 640Solubility InsolubleMohs Hardness @20°C 8Specific Gravity (g/cc) 2.6 to 3.2~7.5 to 8.5Mica, a chemically complex mineral, is an important electrical insulating material with the added advantage of high resistance to high temperatures. Besides, it is flexible, tough, transparent and chemically stable.