igneous
Diorite
Phaneritic intermediate intrusive igneous rock
Hardness: 6-7 (Mohs scale), Color: Salt-and-pepper (mottled black and white), Luster: Vitreous to dull, Structure: Course-grained phaneritic, Cleavage: Present in constituent minerals (amphibole and plagioclase).
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Salt-and-pepper (mottled black and white), Luster: Vitreous to dull, Structure: Course-grained phaneritic, Cleavage: Present in constituent minerals (amphibole and plagioclase).
Formation & geological history
Formed by the slow cooling of intermediate-to-mafic underground magma. It often occurs in volcanic arcs and mountain building zones (orogenic belts).
Uses & applications
Used primarily as crushed stone for road construction and drainage. High-quality specimens are polished for use as ornamental stone, building facings, and monuments.
Geological facts
Diorite is often referred to as 'salt and pepper rock'. Historically, it was used by ancient civilizations like the Egyptians and Sumerians for statues and stelas because of its extreme hardness.
Field identification & locations
Identified by its medium to coarse salt-and-pepper grain distribution. Look for it in areas associated with batholiths or volcanic mountain ranges like the Andes.
