igneous
Granite River Rock
Phaneritic Felsic Igneous Rock (Granite)
Hardness: 6-7 on Mohs scale. Color: Light grey with salt-and-pepper speckling of black/dark grey minerals. Luster: Dull (weathered) to vitreous (on fresh surfaces). Structure: Phaneritic (visible crystals).
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull (weathered) to vitreous (on fresh surfaces)
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Light grey with salt-and-pepper speckling of black/dark grey minerals. Luster: Dull (weathered) to vitreous (on fresh surfaces). Structure: Phaneritic (visible crystals).
Formation & geological history
Granite forms from the slow crystallization of magma below Earth's surface. This specific specimen has been rounded and smoothed by water transport (river or glacial action) during the Quaternary period.
Uses & applications
Used extensively in landscaping, garden decoration, construction aggregate, and as a durable material for polished countertops and monuments.
Geological facts
Granite is the most common rock found in the Earth's continental crust. Because it is very hard and resistant to erosion, it often forms the core of many mountain ranges.
Field identification & locations
Identified by its phaneritic texture where individual grains of quartz, feldspar, and biotite are visible. This specimen is easily found in riverbeds, glacial tills, and landscaping supply yards.
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