igneous
Granite Pebble
Granite (Plutonic Igneous Rock)
Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, grey, and black. Luster: Vitreous to dull (shiny when wet or polished). Texture: Phaneritic (coarse-grained coarse crystalline structure). Specific gravity: 2.63-2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled pink, white, grey, and black
- Luster
- Vitreous to dull (shiny when wet or polished)
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, grey, and black. Luster: Vitreous to dull (shiny when wet or polished). Texture: Phaneritic (coarse-grained coarse crystalline structure). Specific gravity: 2.63-2.75.
Formation & geological history
Formed through the slow cooling and crystallization of felsic magma deep beneath Earth's surface (intrusive plutonic origin). Smooth rounded shape developed via river or wave erosion.
Uses & applications
Tumbled stones are used for rock collections, decorative landscaping, crafts, and aquarium gravel. Larger granite deposits are mined for construction, countertops, and monuments.
Geological facts
Granite makes up a large portion of Earth's continental crust. The pink hue in granite comes from orthoclase potassium feldspar, while translucent zones are quartz and dark specks are biotite mica or hornblende.
Field identification & locations
Identified by its distinctive speckled 'salt-and-pepper' appearance containing interlocking mineral grains of quartz and feldspar. Common along riverbeds, beaches, and glaciated regions worldwide.
