Rock Crystal
Colorless and transparent rock crystal is the most widely distributed variety of quartz, one of the most common minerals of the Earth’s crust. The crystals are usually found as colorless hexagonal prisms, with pyramidal ends and striations perpendicular to their length, and they are often twinned. It is nothing but Silicon dioxide with hardness 7 on the Moh’s scale. Crystal balls made of rock crystal have been used for long time to predict the future and for purifications.