igneous
Granite
Granitoid
Hardness: 6-7 on Mohs scale. Color: Phaneritic texture with salt-and-pepper appearance, featuring pink K-feldspar, white plagioclase, black biotite, and gray quartz. Luster: Dull to vitreous. Crystal structure: Massive, phaneritic (large visible crystals).
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Phaneritic texture with salt-and-pepper appearance, featuring pink K-feldspar, white plagioclase, black biotite, and gray quartz. Luster: Dull to vitreous. Crystal structure: Massive, phaneritic (large visible crystals).
Formation & geological history
Formed through the slow crystallization of magma below the Earth's surface (intrusive). This specific specimen appears to be a river-worn or beach-worn cobble, having undergone physical weathering and transport.
Uses & applications
Widely used as an architectural stone, in construction (curbstones, gravel), and for countertops. It is also a staple for lapidary tumbling and geological education.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Its composition of quartz makes it highly resistant to chemical weathering, which is why it often survives as smooth pebbles in riverbeds.
Field identification & locations
Identify in the field by looking for a 'salt and pepper' look with interlocking crystals of different colors. It is commonly found in mountainous or glaciated regions across North America, Europe, and Asia.
