Fracture

The way a mineral fractures can sometimes help to identify it. Most fractures can be described by the following terms:

Uneven	Rough or irregular surface
Conchoidal	"Shell-like," with a smooth curved surface.
Hackly	Sharp, jagged surfaces like broken metal.
Splintery	Forming elongated splinters (applies to fibrous minerals).
Earthy	Breaking like clay or chalk.

Chesterman, p. 32

Sources

• Chesterman, Charles W. The Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf: New York (1987)