Topaz
Marambaia
Mina Gerais, Brazil
This specimen measures 6.5cm x 4cm
Topaz Al2SiO4(F,OH)2
Nesosilicates; aluminum fluorsilicate
Color and Luster: White, colorless, yellow, pink, bluish, greenish; vitreous; streak colorless
Hardness: 8
Cleavage: Perfect, one basal direction
Fracture: Subconchoidal, uneven
Crystals: Orthorhombic; usually in stubby to medium-long prismtic crystals striated lengthwise; also granular, massive
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals