Quartz is composed of the simplest silicon dioxide, glassy luster, no cleavage surface, but with a shell-like fracture. Microcrystalline quartz is called chalcedony, agate or jasper. Pure quartz is colorless, but it shows different colors because of impurities often containing transition elements. Quartz is very stable and not easy to weathering or change into other minerals. According to the crystallinity of SiO 2, it can be divided into single crystal quartz and polycrystalline quartzite. Gloss: Glass gloss. Colour: No, white, with a little grey, yellow to orange, purple, deep purple, pink, grey brown, brown, black. Stripe: White. Specific gravity: 2.65 ~ 2.66. Category: Metamorphic rock, metamorphosed from sandstone.