Colour, characteristics:

Colour grey, brownish, older varieties mostly greenish.

- Light-coloured minerals: 60-85%

Of which:

Feldspars: 80-100%

Of which:

-alkali feldspar: 0-35%

-Plagioclase feldspar: 65-100%

Quartz 0-20% or Foide 0-10%

- Dark minerals: 15-40%

- Minor minerals:

hornblende, pyroxene, biotite, olivine, magnetite, apatite, zircon

Formation:

By relatively rapid cooling of a rock melt that has penetrated to the earth's surface.

Locations:

Rhineland-Palatinate, Westerwald, Siebengebirge, France (Auvergne, Vosges), Scotland, Romania, USA (Rocky Mountains)

Products:

Used for gravel and chippings due to the high degree of utilisation.