Greisen

The Greisen is a term from the Saxon miners' language and stands for grain, mostly gray rocks that are composed primarily of quartz and are often closely associated with hermaphrodites.

Within the old men, a distinction between

• Mica Greisen
• Topaz Greisen
• Tourmaline Greisen

The old men arises from the fact that a granitic rock body is converted by pneumatolysis in its highest -reaching parts. In this case, fluorine, tungsten, tin, and lithium-containing gas-rich melts penetrate into corridors and columns and convert the available there feldspars to quartz, mica, and cassiterite. Also, tourmaline, topaz and wolframite is found in old men.

Some old people are important because of their content or their entrainment of tin and tungsten. Larger deposits also exist in Cornwall and in the Ore Mountains