igneous
Granodiorite
Granodiorite (intermediate intrusive igneous rock containing plagioclase, quartz, and K-feldspar)
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled grey, white, and black); Luster: Phaneritic (crystalline visible to the eye); Structure: Granular/Massive; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (mottled grey, white, and black)
- Luster
- Phaneritic (crystalline visible to the eye)
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled grey, white, and black); Luster: Phaneritic (crystalline visible to the eye); Structure: Granular/Massive; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the slow cooling of magma deep beneath the Earth's surface (intrusive plutonic). It can range from Precambrian to Cenozoic age, often found in volcanic arcs and mountain roots.
Uses & applications
Used widely in construction as crushed stone for road bases, as dimension stone for buildings, monument engraving, and kitchen countertops (often sold commercially as 'Granite').
Geological facts
Granodiorite is the main component of the Sierra Nevada batholith in California. One of the most famous historical objects carved from granodiorite is the Rosetta Stone, which was used to decipher Egyptian hieroglyphs.
Field identification & locations
Identify by its phaneritic (visible crystal) texture and 'salt and pepper' look. Unlike granite, it contains more plagioclase feldspar than orthoclase. Look for light-colored feldspar/quartz mixed with dark biotite or hornblende.
