Also known as chromium oxide, chromium oxide, molecular weight 151.99. Department of hexagonal system, green powder. Density 5.21g/cm3, Mohs hardness of 8.5 to 9, close to corundum (Al2O3), second only to diamond, and more than quartz SiO2, Topaz Al2〕 〔SiO4 also known as chrome oxide green chromium oxide, chromium oxide, molecular weight 151.99. Department of hexagonal system, green powder. Density 5.21g/cm3, Mohs hardness of 8.5 to 9, close to corundum (Al2O3), second only to diamond, and more than quartz SiO2, Topaz Al2 〔SiO4〕 (F, OH) 2 and zircon  ZrSiO4). Refractive index of 2.5 (good cover ratio), specific heat capacity (20 ℃) / 0.17J / (g K).