Diorite
“Salt-and-pepper plutonic rock”
Igneous
Diorite is a coarse-grained intrusive igneous rock with a distinctive speckled black-and-white appearance. It forms deep underground from intermediate magma and sits compositionally between granite and gabbro on the igneous spectrum.
Composition
plagioclase feldspar, hornblende, biotite, pyroxene
Where Found
Andes Mountains, Scotland, Minnesota (USA), Corsica (France)
Mohs Hardness
6-7
Fun Fact
The Code of Hammurabi — one of the oldest written legal codes in history — was carved into a pillar of polished diorite around 1750 BCE.
Test Your Knowledge
Why are large, pure bodies of diorite relatively uncommon in the geological record?
Related Specimens
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