igneous
Granite Cobble
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale; Color: Pink, white, and grey; Luster: Dull (weathered) to vitreous (on fresh surfaces); Crystal structure: Granular/Phaneritic; Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, white, and grey
- Luster
- Dull (weathered) to vitreous (on fresh surfaces)
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, white, and grey; Luster: Dull (weathered) to vitreous (on fresh surfaces); Crystal structure: Granular/Phaneritic; Specific gravity: 2.63 to 2.75
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface. This specific specimen has been further shaped into a rounded cobble by water erosion, likely in a river or beach environment.
Uses & applications
Used in construction, countertops, monuments, and as decorative landscaping stones.
Geological facts
Granite is the primary component of the continental crust. The pink color in this specimen is due to the presence of potassium feldspar (orthoclase).
Field identification & locations
Identify by its interlocking mineral grains (quartz, feldspar, and mica) and its hardness—it cannot be scratched by a steel knife. Commonly found in mountainous regions or glacial deposits.
