igneous
River Pebble (Granitic / Quartzite Pebble)
Quartz-Feldspar Aggregate (SiO2 / KAlSi3O8)
Hardness: 6-7 on Mohs scale; Color: Gray, pinkish-brown, and dull green tones; Luster: Sub-vitreous to earthy; Cleavage: None (conchoidal to irregular fracture); Structure: Fine to medium-grained aggregate
- Hardness
- 6-7 on Mohs scale
- Color
- Gray, pinkish-brown, and dull green tones
- Luster
- Sub-vitreous to earthy
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Gray, pinkish-brown, and dull green tones; Luster: Sub-vitreous to earthy; Cleavage: None (conchoidal to irregular fracture); Structure: Fine to medium-grained aggregate
Formation & geological history
Formed through mechanical weathering and stream-transport erosion of granitic or metamorphic parent rocks. High-energy aqueous environments (riverbeds, shorelines) abrade and smooth the specimen into a rounded pebble over long periods.
Uses & applications
Commonly used as construction aggregate, landscaping gravel, decorative stone, or casual pocket stones for amateur collectors.
Geological facts
Stream-rounded pebbles can travel hundreds of miles from their original bedrock sources, preserving fragments of ancient mountain-building events.
Field identification & locations
Identify by its rounded, smooth contours resulting from water abrasion, composite mineral grains (quartz, feldspar), and durable hardness. Commonly found along riverbanks, beaches, and glacial till deposits worldwide.
