sedimentary

Chert Pebble (Yellow/Brown Jasper variety)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Yellow-brown, tan, or ochre; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 6
Color: Yellow-brown, tan, or ochre
Luster: Waxy to dull

Identified March 8, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Yellow-brown, tan, or ochre; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed through the precipitation of silica in sedimentary environments, often as nodules in limestone or chalk beds. This specific specimen has been water-worn into a rounded pebble, showing age through environmental erosion.

Uses & applications

Historically used for making stone tools (flintknapping); currently used in decorative gravel, lapidary work (tumbling/polishing), and as a common component in stream beds.

Geological facts

Chert and Jasper are essentially the same material chemically; Jasper specifically refers to the opaque, colored varieties (often from iron oxides). It is one of the most durable and common stones found in riverbeds worldwide.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and its smooth, waxy feel. It is commonly found in gravel pits, riverbanks, and beaches. Collectors look for unique banding or patterns.