Old men
Greisengang with cassiterite and arsenopyrite in granite from Geyer , Ore Mountains
The old people is a term from the Saxon miners' language and is grainy, mostly gray rocks composed mainly of quartz exist and often work closely with hermaphrodites are connected.
Within the old men one differentiates between
- Mica Gels
- Topaz trips
- Tourmaline trips
Greisen is created by the fact that a granitic rock body is transformed in its highest parts by pneumatolysis . Fluids rich in fluorine , tungsten , tin and lithium penetrate into passages and crevices and convert the feldspars there into quartz, mica and cassiterite . Tourmaline, topaz and wolframite can also be found in Greisen.
Some old men are important because of their salary or the fact that they carry tin and tungsten. There are larger deposits in Cornwall and in the Ore Mountains .
literature
- Hans Murawski and Wilhelm Meyer : Geological dictionary . 10., rework. u. exp. Ed., 278, Enke Verlag, Stuttgart 1998 ISBN 3-432-84100-0 .