igneous
Granite Pebble
Granite (Felsic Plutonic Rock)
Hardness: 6-7 (Mohs); Color: Salt-and-pepper (white, grey, and black); Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 (Mohs)
- Color
- Salt-and-pepper (white, grey, and black)
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 (Mohs); Color: Salt-and-pepper (white, grey, and black); Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific Gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen is an water-worn pebble, likely rounded by river or beach erosion.
Uses & applications
Used widely in construction (countertops, flooring), monuments, and as decorative landscaping stones.
Geological facts
Granite makes up a large portion of the Earth's continental crust. The black spots in this specimen are likely biotite or hornblende, while the white is quartz and feldspar.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible interlocking crystals. Common in mountain ranges and glacial deposits. For collectors, look for hard, speckled rocks that cannot be scratched by a steel knife.
