Keywords |
  • Geology


Gneiss is metamorphic rock generally composed of dark beds of ferro-magnesium minerals (micas, amphiboles) and light beds of quartz and feldspars. Gneiss can also contain garnet, sillimanite, cordierite etc. Augen gneisses are characterised by feldspar metacrystals or by quartz and feldspar aggregates.


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