igneous
Granite
Phaneritic plutonic rock (Quartz + Alkali Feldspar + Plagioclase Feldspar)
Hardness: 6 to 7 (Mohs scale); Color: Pinkish-tan with black speckles; Luster: Dull/Granular (sub-vitreous on fresh surfaces); Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (fractures irregularly)
- Hardness
- 6 to 7 (Mohs scale)
- Color
- Pinkish-tan with black speckles
- Luster
- Dull/Granular (sub-vitreous on fresh surfaces)
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Physical properties
Hardness: 6 to 7 (Mohs scale); Color: Pinkish-tan with black speckles; Luster: Dull/Granular (sub-vitreous on fresh surfaces); Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (fractures irregularly)
Formation & geological history
Formed through the slow crystallization of magma below the Earth's surface. This specimen appears to be water-worn or tumbled, likely from a glacial or river deposit. Common in continental crust and mountain ranges.
Uses & applications
Used in construction, countertops, monuments, and as crushed stone for road base. Tumbled pieces are common in landscape gardening and rock collections.
Geological facts
Granite is the primary rock of Earth's continental crust. Its pink color usually comes from potassium-rich orthoclase feldspar, while the black grains are typically biotite mica or hornblende.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals. It is much harder than steel and cannot be scratched by a knife. Found worldwide in high-elevation or glaciated regions.
