igneous
Granite
Granite (Felsic Plutonic Rock)
Hardness: 6-7 on Mohs scale; Color: Pinkish-red (orthoclase), gray, and black (biotite/amphibole); Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63-2.75
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to vitreous
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pinkish-red (orthoclase), gray, and black (biotite/amphibole); Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface. This specimen appears to be a weathered fragment of pink granite, likely millions to billions of years old from an intrusive igneous body.
Uses & applications
Widely used in construction, countertops, monuments, curbing, and as crushed stone for road base. Minor use in high-end garden lapidary.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in South Dakota.
Field identification & locations
Identify by its interlocking crystalline texture containing pink feldspar, clear-gray quartz, and dark specks of mica or hornblende. Can be found in mountainous regions or glacial till worldwide.
