igneous
Granite Cobble
Granite
Hardness: 6-7 (Mohs scale); Color: Salt and pepper appearance with pinkish-tan tones; Luster: Variable, dull surface but sparkly minerals; Crystal structure: Phaneritic (visible crystals); Cleavage: None (the minerals within have cleavage, but the rock breaks irregularly).
- Hardness
- 6-7 (Mohs scale)
- Color
- Salt and pepper appearance with pinkish-tan tones
- Luster
- Variable, dull surface but sparkly minerals
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Salt and pepper appearance with pinkish-tan tones; Luster: Variable, dull surface but sparkly minerals; Crystal structure: Phaneritic (visible crystals); Cleavage: None (the minerals within have cleavage, but the rock breaks irregularly).
Formation & geological history
Formed through the slow crystallization of magma below the Earth's surface. This specific specimen has been smoothed and rounded by water erosion (alluvial or glacial action). Its age can range from millions to billions of years.
Uses & applications
In this rounded form, they are used for landscaping, decorative garden stones, and construction aggregate. Quarried granite is used for countertops and monuments.
Geological facts
Granite is the most common igneous rock in the Earth's continental crust. It contains significant amounts of quartz and feldspar, making it highly resistant to weathering.
Field identification & locations
Identify by its interlocking texture of white, grey, pink, and black minerals. Commonly found in riverbeds, glaciated regions, and mountain ranges. Collectors look for unique mineral patterns or signs of glacial transport.
