A common lump of Quartz showing
conchoidal fracture and vitreous luster.
A short prismatic crystal of Quartz in dolomite. This is an example of a
Herkimer Diamond from New York.
Prismatic crystals of Quartz terminated with pyramids.
A divergent cluster of Quartz prisms.
CHEMISTRY - SiO2 Silicon dioxide
CRYSTALLOGRAPHY - Hexagonal - Trigonal trapezohedral
CRYSTAL GROWTH AND HABITS - Crystals can develop in a variety of ways. Most commonly as hexagonal prisms terminated with pyramids. It is also commonly microcrystalline as in chalcedony and chert.
COLOR AND OTHER OPTICAL PROPERTIES Quartz has a wide range of colors as it is easily tinted by minor amounts of impurities. Colors include white, pink, yellow, brown, green, purple, gray and black. It is transparent to nearly opaque.
HARDNESS - 7 SPECIFIC GRAVITY - 2.65
LUSTER - vitreous STREAK - white
BREAKABILITY Conchoidal fracture, brittle
OCCURRENCE Quartz is very common is the felsic igneous rocks like granite and granitic pegmatites. It is the dominant mineral in most sandstones and quartzites.