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Diorite


What is Diorite?



Diorite is a coarse-grained, intrusive igneous rock that is intermediate in composition between granite and gabbro. It’s composition is very similar to the fine-grained extrusive rock known as andesite.

Diorite is composed primarily of plagioclase feldspar, amphibole, and pyroxine minerals with small amounts of biotite mica. It typically contains very little quartz.

When identifying diorite look for a rock that as abundant white and dark minerals - a “salt and pepper” appearance. With a hand lens look for the cleavage faces of plagioclase feldspar intersecting at oblique angles. Also, look for vitreous cleavage faces on the dark amphibole minerals.


More Igneous Rocks
  Peridotite
  Pumice
  Scoria
  Pegmatite
  Obsidian
  Gabbro
  Granite
  Basalt



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