igneous
Pink Granite (River Pebble)
Phaneritic Felsic Igneous Rock
Hardness: 6-7 (Mohs); Color: Pink to orange-red with black and grey specks; Luster: Dull (weathered) to vitreous (fresh break); Crystal Structure: Phaneritic (visible crystals of quartz, K-feldspar, and mica); Cleavage: None for the rock as a whole
- Hardness
- 6-7 (Mohs)
- Color
- Pink to orange-red with black and grey specks
- Luster
- Dull (weathered) to vitreous (fresh break)
Identified More igneous →
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Physical properties
Hardness: 6-7 (Mohs); Color: Pink to orange-red with black and grey specks; Luster: Dull (weathered) to vitreous (fresh break); Crystal Structure: Phaneritic (visible crystals of quartz, K-feldspar, and mica); Cleavage: None for the rock as a whole
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen has been rounded by fluvial processes (water erosion in a river or glacial stream) over thousands to millions of years.
Uses & applications
Used widely in construction as crushed stone, dimension stone for countertops and monuments, and as decorative landscaping gravel.
Geological facts
The pink color comes specifically from Potassium Feldspar (Orthoclase). Granite makes up the majority of the Earth's continental crust and is incredibly resistant to weathering, which is why it often survives as rounded pebbles in riverbeds.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance with a pinkish hue and hardness; it will easily scratch glass. Commonly found in mountainous regions, glacial till, or riverbeds downstream from igneous outcrops.
