igneous
Granite
Phaneritic intrusive igneous rock
Hardness: 6-7 (Mohs scale), Color: Pinkish-red (orthoclase feldspar) with grey (quartz) and speckles of black (biotite/hornblende), Luster: Dull to vitreous, Crystal structure: Granular/Phaneritic, Cleavage: None (fractures), Specific gravity: 2.63-2.75
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Pinkish-red (orthoclase feldspar) with grey (quartz) and speckles of black (biotite/hornblende), Luster: Dull to vitreous, Crystal structure: Granular/Phaneritic, Cleavage: None (fractures), Specific gravity: 2.63-2.75
Formation & geological history
Formed by the slow crystallization of magma below the Earth's surface in plutons. This specimen shows a contact zone or hydrothermal alteration, giving it the distinctive pink and grey banding.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stone, curbing, and as a decorative building stone.
Geological facts
Granite makes up the majority of the Earth's continental crust. Its pink color is usually due to an abundance of potassium feldspar. It is one of the hardest and most durable natural stones available.
Field identification & locations
Identify in the field by its coarse-grained crystal texture where individual minerals are visible. It is commonly found in mountain ranges and glacial deposits (glacial erratics). Look for the interlocking 'jigsaw' pattern of crystals.
