Striation
As striation is referred to in the mineralogy the strips or grooves on the surface of minerals . Most of the time, these stripes run parallel to each other, sometimes triangular or crossed. Striation is an important criterion in determining certain minerals. Stripes should not be confused with adhesions that have irregular lines and a different color.
Clear stripes on a pyrite cube with different orientation on each side.
Pyrite with triangular stripes
Striations in a crystal group of albite .
Irregular lines in the lepidolite (no striations).
The striation is caused by different growth rates during crystal growth . This creates juxtapositions of the crystal surfaces .
Another possibility for the formation of striations is the formation of twins , especially with lamellar or polysynthetic twinning.
In rocks, the striations can result from mechanical influences, for example from glaciers . See also: flow stripes .
literature
- JC Gray: EARNING THEIR STRIPES - What striations can tell us about a mineral . In: The Georgia Mineral Society . 2003, p. 9-10 ( [1] [PDF]).
Web links
- Mineral Atlas: Striations (Wiki)
- minerals.net (English)