igneous
Granite
Phaneritic Felsic Igneous Rock (composed of SiO2, KAlSi3O8, NaAlSi3O8)
Hardness: 6-7 Mohs; Color: Light gray with salt-and-pepper texture; Luster: Dull/Granular with reflective mineral flecks; Crystal Structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific Gravity: 2.63 - 2.75
- Hardness
- 6-7 Mohs
- Color
- Light gray with salt-and-pepper texture
- Luster
- Dull/Granular with reflective mineral flecks
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Physical properties
Hardness: 6-7 Mohs; Color: Light gray with salt-and-pepper texture; Luster: Dull/Granular with reflective mineral flecks; Crystal Structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific Gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface (intrusive). They take millions of years to cool, allowing for large crystal growth. Found in continental crust, often appearing in mountains through erosion.
Uses & applications
Extensively used in construction (countertops, flooring, monuments, paving), crushed stone for roads, and as a durable outdoor landscaping material.
Geological facts
Granite is the most common igneous rock found on the planet's surface and makes up a massive part of the continental crust. It is incredibly resistant to weathering and pressure.
Field identification & locations
Identify by its interlocking 'mosaic' of visible crystals, primarily light-colored quartz and feldspar with dark mica or hornblende. Commonly found in mountain ranges or as glacial erratics in riverbeds.
