Chemical Formula: SiO2 Mineral Name: Chalcedony Color: Varying shades of Red Hardness: 7 Specific Gravity: 2.65 - 2.66 A cryptocrystalline quartz, carnelian's red color is due to the presence of iron impurities in the form of iron oxide. The stone is usually cut into cabochon, or into beads, and is also used for intaglios and cameos. Carnelian is found in the regions of Arabia and Egypt, India, China, Colombia, Saxony, Scotland, West Germany and USA. Beautiful imitations of cornelian are made by the staining of agate. It is used in making attractive jewelry and decorative pieces.