igneous
Granite Pebble (River-worn Granite)
Granite
AI-generated identification · may be incorrectHardness: 6-7 on Mohs scale; Color: Mottled pink, white, gray, and black; Luster: Vitreous to dull on weathered surfaces; Texture: Phaneritic (coarse-grained), rounded and weathered pebble; Specific Gravity: 2.63 - 2.75 g/cm³; Composition: Quartz, alkali feldspar, plagioclase feldspar, and minor biotite/amphibole.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled pink, white, gray, and black
- Luster
- Vitreous to dull on weathered surfaces
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Mottled pink, white, gray, and black; Luster: Vitreous to dull on weathered surfaces; Texture: Phaneritic (coarse-grained), rounded and weathered pebble; Specific Gravity: 2.63 - 2.75 g/cm³; Composition: Quartz, alkali feldspar, plagioclase feldspar, and minor biotite/amphibole.
Formation & geological history
Formed by the slow crystallization of felsic silica-rich magma deep underground beneath continental crust (plutonic). This particular specimen was eroded from bedrock and smoothed by mechanical weathering in a river or glacial stream.
Uses & applications
Widely used in crushed form for road construction and concrete aggregate; polished slabs are used for architectural facades, countertops, and monument stones. This specimen serves educational or landscape decorative purposes.
Geological facts
Granite constitutes much of the continental crust of Earth. Because it cools extremely slowly miles under the Earth's surface, individual mineral crystals have enough time to grow large enough to be clearly visible to the naked eye.
Field identification & locations
Easily identified by its 'salt-and-pepper' to pink granular appearance and interlocking crystalline texture that cannot be easily scratched with a steel nail. Extremely abundant in mountainous areas, glacial drift, stream gravels, and riverbeds globally.
