igneous
Dark, speckled coarse-grained rock; likely diorite
Diorite, an intrusive igneous rock composed mainly of plagioclase feldspar and hornblende or other dark minerals
AI-generated identification · may be incorrectDark gray-green with pale mineral flecks and a granular texture; typical diorite has Mohs hardness around 6–7 and interlocking crystals. The photo does not show enough detail to confirm mineral composition or luster.
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Physical properties
Dark gray-green with pale mineral flecks and a granular texture; typical diorite has Mohs hardness around 6–7 and interlocking crystals. The photo does not show enough detail to confirm mineral composition or luster.
Formation & geological history
Forms when magma cools slowly underground, allowing visible crystals to grow; diorite occurs in intrusive bodies of many geological ages.
Uses & applications
Diorite is used as crushed aggregate, building or decorative stone, and occasionally for polished objects.
Geological facts
Diorite is often informally called “black granite,” though it is compositionally distinct from granite.
Field identification & locations
Look for interlocking light feldspar and dark amphibole grains; a close-up or fresh broken surface would help distinguish it from other dark speckled rocks. Diorite is widespread in continental mountain belts and intrusive complexes.
