igneous
Granite Pebble
Granitoid (Felsic Plutonic Rock)
Hardness: 6-7 on Mohs scale; Color: Mottled pink, white, gray, and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained); Cleavage: Dependent on mineral constituents; Specific Gravity: 2.63-2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled pink, white, gray, and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Mottled pink, white, gray, and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained); Cleavage: Dependent on mineral constituents; Specific Gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground. This specific specimen appears water-worn, suggesting a secondary transport process by rivers or coastal action. Age can range from millions to billions of years.
Uses & applications
Used in construction, countertops, monuments, and as decorative landscaping gravel. Small pebbles like this are often gathered for pebble art or aquarium substrate.
Geological facts
Granite makes up the majority of the Earth's continental crust. It contains at least 20 percent quartz by volume, which contributes to its high durability and resistance to weathering.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible interlocking crystals. It is found in mountain ranges and riverbeds globally. Collectors look for unique mineral inclusions like large feldspar crystals or mica flakes.
