igneous
Granite Cobble
Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Hardness: 6-7 Mohs; Color: Tan/buff exterior with white/grey interior; Luster: Dull (weathered) to Vitreous (internal); Crystal Structure: Phaneritic (visible grains); Specific Gravity: 2.6-2.7
- Hardness
- 6-7 Mohs
- Color
- Tan/buff exterior with white/grey interior
- Luster
- Dull (weathered) to Vitreous (internal)
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Tan/buff exterior with white/grey interior; Luster: Dull (weathered) to Vitreous (internal); Crystal Structure: Phaneritic (visible grains); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through slow crystallization of magma below Earth's surface. This specimen has been rounded by fluvial activity (river or stream transport) and exhibits a weathered outer rind (patina) due to long-term exposure to the elements.
Uses & applications
Commonly used in crushed form for road construction, as architectural veneer, or as decorative landscaping stones.
Geological facts
Granite comprises a significant portion of Continental Crust. This specific round shape is the result of 'abrasion'—the geological process where stones collide in moving water, wearing down sharp edges over centuries.
Field identification & locations
Identify by its coarse-grained 'salt and pepper' texture and its inability to be scratched by a steel knife. Common in riverbeds, glacial tills, and mountainous regions worldwide.
