Quartz Crystal is a colorless and transparent large-scale quartz crystal mineral. Its main chemical component is silicon dioxide. The chemical formula is SiO2. The crystal is colorless, purple, yellow, green, and smoke. Glass luster. Transparent to translucent. Hardness 7. Brittle. No cleavage. Crystal density: 2.56-2.66 g/cm3. Crystal refractive index: 1.544-1.553, almost within this range. Crystal dispersion: 0.013. The melting point of the crystal is 1713°C.