igneous
Granite Pebble
Granite
Hardness: 6-7 Mohs; Color: Salt and pepper appearance with pink, white, and black grains; Luster: Dull (weathered) to vitreous (on fresh breaks); Structure: Phaneritic (visible crystals); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Luster
- Dull (weathered) to vitreous (on fresh breaks)
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper appearance with pink, white, and black grains; Luster: Dull (weathered) to vitreous (on fresh breaks); Structure: Phaneritic (visible crystals); Specific Gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep beneath the Earth's surface (plutonic). This specific specimen has been rounded by water erosion (fluvial or beach action). Pieces of granite can date back hundreds of millions to billions of years.
Uses & applications
Crushed stone for construction, architectural veneers, countertops (in slab form), and decorative landscaping.
Geological facts
Granite makes up a large portion of the Earth's continental crust. The pink color in this specimen comes from potassium feldspar (orthoclase).
Field identification & locations
Identify in the field by the 'speckled' look of interlocking quartz, feldspar, and biotite mica crystals. Commonly found in mountainous regions or as glacial erratic pebbles in beaches and riverbeds.
