igneous
Granite
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper look with pink (orthoclase), white (plagioclase), clear/gray (quartz), and black (biotite/hornblende). Luster: Vitreous to dull. Structure: Coarse-grained phaneritic crystals.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper look with pink (orthoclase), white (plagioclase), clear/gray (quartz), and black (biotite/hornblende). Luster: Vitreous to dull. Structure: Coarse-grained phaneritic crystals.
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (intruded into the crust). Crystals have time to grow large enough to be seen with the naked eye. Age can range from Pre-Cambrian to Cenozoic.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stone, monuments, curbing, and as crushed stone for road base.
Geological facts
Granite makes up a large portion of the Earth's continental crust. It is one of the hardest and most durable natural stones, which is why it has been used in architecture since Ancient Egypt. The word comes from the Latin 'granum', meaning a grain.
Field identification & locations
Identify by its interlocking 'mosaic' of different colored minerals and lack of layering (foliation). It is found in mountain ranges and continental shields worldwide. Look for the distinctive pink potassium feldspar and glassy quartz grains.
