igneous
Granite
Granite (composed primarily of Quartz SiO2 and Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8))
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (white, grey, and black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.65-2.75.
- Hardness
- 6-7 (Mohs scale)
- Color
- Salt and pepper (white, grey, and black)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Salt and pepper (white, grey, and black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.65-2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. It is a coarse-grained intrusive rock usually associated with continental crust formation over millions of years.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, and monuments due to its durability and aesthetic appeal.
Geological facts
Granite is one of the hardest substances in the world, second only to diamonds. It makes up a large part of the continental crust and is vital in understanding the movement of tectonic plates.
Field identification & locations
Identify in the field by its speckled 'salt and pepper' look and interlocked visible crystals. It is found in mountain ranges and continental shields. Collectors should look for unique mineral inclusions like tourmaline or large feldspar phenocrysts.
