Quartz "an ancient German word meaning hard. Quartz stone is the most common mineral in continental crust rocks. It has the simplest chemical formula, which is silicon dioxide (SiO2). Geologically, quartz turns into crystals when subjected to severe pressure as its Crystal deposits were formed millions of years ago. It is used to decorate artistic pieces and Jewelry. Stone : Quartz Shape: Elliptical Weight:2.30 Carat Size (mm) : 10 x 8 Color: Brownish / Black Hardness: 7 Orogin: Madagascar