igneous
Granite Boulder (and Tree Root)
Granite
Hardness: 6-7 on Mohs scale; Color: Gray to pinkish with speckled black grains; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained, interlocking crystals); Cleavage: Poor
- Hardness
- 6-7 on Mohs scale
- Color
- Gray to pinkish with speckled black grains
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Gray to pinkish with speckled black grains; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained, interlocking crystals); Cleavage: Poor
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (plutonic) millions of years ago, later exposed at the surface by erosion and glacial transport.
Uses & applications
Used widely as dimension stone, building material, decorative landscaping boulders, crushed stone for construction, and granite countertops.
Geological facts
Granite makes up a major part of the continental crust. Glacial erratics—large granite boulders moved by ancient glaciers—are commonly found isolated in forests and fields worldwide.
Field identification & locations
Identify in the field by its hard, coarse-grained texture visible to the naked eye containing quartz, feldspar, and mica. Found in mountain ranges, shield areas, and glacial till deposits.
