igneous
Likely diorite (small hand specimen)
Diorite; chiefly plagioclase feldspar and hornblende, often with biotite
AI-generated identification · may be incorrectCoarse, mottled gray-and-white crystals with dark mafic minerals; typically hardness 6–7, nonmetallic luster, and interlocking crystalline texture. The image is too small to confirm mineral identification or cleavage.
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Physical properties
Coarse, mottled gray-and-white crystals with dark mafic minerals; typically hardness 6–7, nonmetallic luster, and interlocking crystalline texture. The image is too small to confirm mineral identification or cleavage.
Formation & geological history
Diorite forms when intermediate-composition magma cools slowly underground, allowing visible crystals to grow. Its age depends on the source locality; diorite occurs in plutons of many geological ages.
Uses & applications
Used as dimension stone, aggregate, and occasionally decorative or carved stone; this small fragment is mainly a teaching or collector specimen.
Geological facts
Diorite is commonly called a “salt-and-pepper” rock because light feldspar contrasts with dark amphibole or biotite.
Field identification & locations
Look for coarse interlocking crystals and a roughly balanced mix of light and dark minerals; distinguish it from granite, which commonly contains quartz and potassium feldspar. Found in intrusive igneous bodies worldwide.
