igneous
Granite Pebble
Granite (Felsic Plutonic Rock)
Hardness: 6-7 on Mohs scale; Color: Mottled tan, cream, and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: No true cleavage in mass, though mineral components (like feldspar) have it.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled tan, cream, and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Mottled tan, cream, and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: No true cleavage in mass, though mineral components (like feldspar) have it.
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This pebble indicates secondary weathering and transport by water, which rounded its edges.
Uses & applications
Used extensively in construction (aggregate, countertops, monuments), landscaping, and as a durable decorative stone.
Geological facts
Granite makes up a significant portion of the Earth's continental crust. It is one of the hardest and most resistant common rocks, which is why it survives as river or beach pebbles after softer rocks have eroded away.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz (clear/grey) and feldspar (cream/tan). Found in mountain ranges and glacial deposits worldwide.
