igneous
Granite
Granitoid (SiO2 typically > 69%)
Hardness: 6-7 Mohs; Color: Light gray, mottled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.65-2.75
- Hardness
- 6-7 Mohs
- Color
- Light gray, mottled
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Light gray, mottled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.65-2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. It is a plutonic rock typical of continental crust, often dating back to various orogenic events across millions of years.
Uses & applications
Extensively used in construction, countertops, floor tiles, paving stones, and as a decorative stone in monuments and landscaping.
Geological facts
Granite is the most common igneous rock found on Earth's surface and makes up a large portion of the continental crust. The Mount Rushmore National Memorial is carved into a granite batholith.
Field identification & locations
Identify by its interlocking crystalline texture and visible speckled appearance of quartz and feldspar. Found globally in mountainous regions where underlying batholiths are exposed.
