igneous
Granite River Stone
Phaneritic Felsic Igneous Rock
Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, pink, and black grains); Luster: Vitreous to dull; Crystal structure: Phaneritic (visible crystals of quartz, feldspar, and mica); Specific gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper (gray, white, pink, and black grains)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, pink, and black grains); Luster: Vitreous to dull; Crystal structure: Phaneritic (visible crystals of quartz, feldspar, and mica); Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground. This specific specimen has been shaped and rounded by water erosion, likely in a river, stream, or glacial environment. Geological age ranges from Precambrian to Cenozoic depending on location.
Uses & applications
Used extensively in construction for countertops, floor tiles, and gravel. These polished river stones are popular for landscaping, garden decor, and as meditative 'worry stones'.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Most granite has been around for millions of years, and it is one of the hardest natural building materials available.
Field identification & locations
Identify in the field by looking for a blocky, granular texture with visible interlocking crystals of different colors. It is found globally in mountainous regions or as glacial 'erratics' in valleys and rivers.
