igneous
Granite Pebble
Granite (Plutonic Igneous Rock)
Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, grey, and black. Luster: Dull to glassy depending on individual mineral grains. Texture: Phaneritic (coarse-grained). Composition: Potassium feldspar (pink), quartz (clear/greyish), plagioclase feldspar, and biotite mica or hornblende (black).
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled pink, white, grey, and black
- Luster
- Dull to glassy depending on individual mineral grains
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, grey, and black. Luster: Dull to glassy depending on individual mineral grains. Texture: Phaneritic (coarse-grained). Composition: Potassium feldspar (pink), quartz (clear/greyish), plagioclase feldspar, and biotite mica or hornblende (black).
Formation & geological history
Formed from the slow crystallization of felsic magma beneath the Earth's surface deep within continental crust. This specific small pebble has been rounded and smoothed through natural stream or beach erosion.
Uses & applications
Granite is widely used as dimension stone, building material, countertops, and crushed stone for road construction. Small river pebbles like this specimen are often collected casually, used in landscaping, or included in aquarium gravel.
Geological facts
Granite makes up a large portion of Earth's continental crust. The pink coloration comes specifically from orthoclase or potassium feldspar minerals within the rock matrix.
Field identification & locations
Identify in the field by its speckled, multicolor 'salt-and-pepper' appearance featuring distinct pink feldspar and translucent quartz grains. Found in gravel beds, rivers, beaches, and glaciated landscapes worldwide.
