igneous
Granodiorite (Cobble/Pebble)
Granodiorite
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (white/grey with black spots). Luster: Phaneritic (crystalline). Structure: Coarse-grained intrusive. Specific Gravity: 2.6-2.7.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (white/grey with black spots)
- Luster
- Phaneritic (crystalline)
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (white/grey with black spots). Luster: Phaneritic (crystalline). Structure: Coarse-grained intrusive. Specific Gravity: 2.6-2.7.
Formation & geological history
Formed from the slow cooling of silica-rich magma beneath the Earth's surface (plutonic). This specific round shape is the result of mechanical weathering and stream/water erosion over time.
Uses & applications
Used in construction as crushed stone, road base, and architectural building stone. High-quality slabs are used for countertops similarly to granite.
Geological facts
Granodiorite is the intermediate rock between granite and diorite. The famous Rosetta Stone was carved from a block of granodiorite.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible crystals of plagioclase feldspar, quartz, and dark biotite or hornblende. Often found in riverbeds or glacial tills.
