igneous
Granodiorite Pebble
Granodiorite
Hardness: 6-7 on Mohs scale. Color: Salt and pepper (mottled gray, white, and black). Luster: Dull to phaneritic. Crystal structure: Medium to coarse-grained phaneritic texture. Cleavage: Distinct in feldspar grains.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (mottled gray, white, and black)
- Luster
- Dull to phaneritic
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt and pepper (mottled gray, white, and black). Luster: Dull to phaneritic. Crystal structure: Medium to coarse-grained phaneritic texture. Cleavage: Distinct in feldspar grains.
Formation & geological history
Formed through the slow cooling of silica-rich magma beneath the Earth's surface (intrusive). This specimen has been rounded and smoothed by water erosion, likely in a riverbed or coastal environment.
Uses & applications
In crushed form, it is used for road base and concrete aggregate. Large deposits are quarried for dimension stone and architectural cladding.
Geological facts
Granodiorite is intermediate between granite and diorite. The famous Rosetta Stone was carved from a slab of granodiorite.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible interlocking crystals. It is richer in plagioclase feldspar than orthoclase. Commonly found in batholiths and mountain ranges like the Sierra Nevada.
