)2O4, with an equiaxed crystal system and a hardness of 7.5 ~ 8. Refractive index 1.75 ~ 1.79, translucent, often dark green, brown, black and other colors.
magnesium-alumina
spinel is a kind of spinel refractory material which is synthesized by using magnesium oxide and alumina as raw materials. This raw material is rarely found in nature, and the industrial magnesia-alumina spinel is all artificially synthesized. Bauxite-based sintered magnesia-alumina spinel is made of high-quality bauxite with Al2O3 content above 76% and light-burned magnesia powder with MgO content above 95%, which is sintered at a high temperature above 18°C in an ultra-high temperature tunnel kiln through multistage homogenization process.