igneous
Granite Cobble
Granite
Hardness: 6-7 (Mohs scale); Color: speckled grey, white, and pink; Luster: dull to vitreous; Structure: phaneritic (coarse-grained); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 (Mohs scale)
- Color
- speckled grey, white, and pink
- Luster
- dull to vitreous
Identified More igneous →
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Physical properties
Hardness: 6-7 (Mohs scale); Color: speckled grey, white, and pink; Luster: dull to vitreous; Structure: phaneritic (coarse-grained); Specific Gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling and crystallization of felsic magma beneath the Earth's surface. This specific specimen has been rounded by mechanical weathering, likely via river or glacial transport.
Uses & applications
Used extensively in construction (aggregate, paving), countertops, curbing, and gravestones. This specific piece is a common decorative garden stone or river rock.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Most granite has been around for hundreds of millions of years, often dating back to the Precambrian era.
Field identification & locations
Identify by its 'salt and pepper' appearance of interlocking crystals (quartz, feldspar, and mica). Found globally in mountainous regions and as glacial till. Collectors value unique colorings or unusually smooth river-worn shapes.
