igneous
Granite
Granite (Felsic Intrusive Igneous Rock)
Hardness: 6-7 Mohs; Color: Pinkish-gray mottled with white and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained); Composition: Quartz, Potassium Feldspar, Plagioclase, and Biotite/Hornblende; Specific Gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Pinkish-gray mottled with white and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Pinkish-gray mottled with white and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained); Composition: Quartz, Potassium Feldspar, Plagioclase, and Biotite/Hornblende; 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 specimen appears to be a glacial erratic, transported and smoothed by ice movements during the Pleistocene epoch.
Uses & applications
Extensively used in construction for countertops, monuments, paving, curbing, and aggregate for road base and concrete.
Geological facts
Granite is the primary component of the Earth's continental crust. Its pink color usually comes from orthoclase feldspar. Large boulders like this are often 'erratics' left behind by receding glaciers thousands of years ago.
Field identification & locations
Identify by its interlocking granular texture where individual mineral grains are visible to the naked eye. Look for the 'salt and pepper' look with pinkish hues. Found globally in continental mountain ranges and shield areas like the Canadian Shield.
