Quartz
Hot Springs, Arkansas

This specimen measures 18cm x 21cm


Quartz      SiO2

Silicates; Silicon dioxide

Color and Luster: White, colorless, and in various shades as follows: rockcrystal, transparent, colorless; amethyst, purple, rose quartz, pink, rose-red; citrine, clear yellow; smoky quartz, plae brown to black; milky quartz, milk white; aventurine, glistening with enclosed scales of mica or hematite; cat's eye, opalescent from inclusions of asbestos; and tigereye, with lusterous yellow to brown parallel fibers; vitreous, greasy luster; streak white

Hardness: 7

Cleavage: Generally none; rarely indistinct rhombohedral parting

Fracture: Conchoidal

Crystals: Hexagonal; usually prismatic crystals striated crosswise and frequently terminated by double rhomohedrons(like hexagonal pyramids); also granular, disseminated, massive

Photo by Mary Sutherland


Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals