sedimentary
River Pebble (Chert/Quartzite)
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs scale); Color: Tan and cream with brown banding; Luster: Waxy to dull pebble surface; Structure: Crypto-crystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 7 (Mohs scale)
- Color
- Tan and cream with brown banding
- Luster
- Waxy to dull pebble surface
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan and cream with brown banding; Luster: Waxy to dull pebble surface; Structure: Crypto-crystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed via the accumulation of silica-rich sediments or the chemical replacement of limestone. This specimen shows significant rounding and smoothing due to fluvial (river) erosion over thousands of years.
Uses & applications
Used primarily as decorative landscaping stone, aggregate in construction, and occasionally for lapidary tumbling for beginners.
Geological facts
River pebbles like this one are often found in ancient riverbeds many miles from current water sources. They are extremely durable due to their high silica content.
Field identification & locations
Identify in the field by its smooth, water-worn texture and hardness (it will scratch glass). Commonly found in riverbanks, coastal beaches, and glacial till.
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