Quartz, most common of all minerals is composed of silicon dioxide, or silica, SiO2. It is an essential component of igneous and metamorphic rocks. The size varies from specimens weighing a metric ton to minute particles that sparkle in rock surfaces. The luster in some specimens is vitreous; in others it is greasy or glossy.
Some specimens are transparent; others are translucent. In pure form, quartz is colorless, but it is commonly colored by impurities. Rock crystal is a colorless form of quartz occurring in distinct crystals. Rose quartz is coarsely crystalline and colored rose red or pink. Smoky quartz occurs in crystals ranging from smoky yellow to dark brown. Amethyst, a semiprecious variety of quartz, is purple or violet.
Quartz crystals exhibit a property called the piezoelectric effect—that is, they produce an electric voltage when pressurized along certain directions of the crystal.
Quartz also rotates the plane of polarized light and is used in polarizing microscopes.
A free flowing granular solid.