igneous
Diorite
Diorite (intermediate intrusive igneous rock)
Phaneritic (coarse-grained) texture, salt-and-pepper appearance, hardness of 6-7 on the Mohs scale, sub-vitreous to dull luster. Composed primarily of plagioclase feldspar and hornblende or biotite.
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Physical properties
Phaneritic (coarse-grained) texture, salt-and-pepper appearance, hardness of 6-7 on the Mohs scale, sub-vitreous to dull luster. Composed primarily of plagioclase feldspar and hornblende or biotite.
Formation & geological history
Forms through the slow cooling of intermediate magma beneath the Earth's surface (plutonic) at volcanic arcs or during mountain-building events (orogeny).
Uses & applications
Commonly used as crushed stone for road construction, as dimension stone for building facades, countertops, and floor tiles. Historically used for sculpture and monumental inscriptions.
Geological facts
The Code of Hammurabi was inscribed on a black diorite stele. It is often confused with granite but lacks the significant quartz content that characterizes true granite.
Field identification & locations
Identifiable by its medium-to-coarse interlocking crystalline texture and approximately equal mix of light and dark minerals. Found in extensive batholiths and mountain ranges like the Andes.
