igneous
Granite Pebble
Granite
Hardness: 6-7 on Mohs scale. Color: Speckled gray, white, pink, and black. Luster: Vitreous to dull. Texture: Phaneritic (medium-grained crystalline pebble rounded by erosion). Mineral content: Quartz, potassium feldspar, plagioclase, biotite, and/or hornblende.
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled gray, white, pink, and black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Speckled gray, white, pink, and black. Luster: Vitreous to dull. Texture: Phaneritic (medium-grained crystalline pebble rounded by erosion). Mineral content: Quartz, potassium feldspar, plagioclase, biotite, and/or hornblende.
Formation & geological history
Formed through the slow crystallization of felsic magma deep beneath the Earth's surface (intrusive igneous rock). Subsequently eroded, transported, and rounded by stream or wave action into a smooth pebble.
Uses & applications
Commonly used in landscaping, decorative stone arrangements, construction aggregates, and aquariums. Larger granite is widely used for kitchen countertops and monuments.
Geological facts
Granite makes up a major portion of the Earth's continental crust. The distinct 'salt-and-pepper' look is caused by dark ferromagnesian minerals mixed with light-colored quartz and feldspar crystals.
Field identification & locations
Easily identified in the field by its speckled phaneritic texture containing visible interlocking crystals of quartz and feldspar, often worn into a pebble shape along rivers or beach shores.
