sedimentary

Rounded gray-green chert (likely silicified limestone)

Microcrystalline quartz/chalcedony (SiO₂), possibly jasper or siliceous limestone

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; pale gray-green with cream and rusty weathering veins, dull to waxy luster, very fine-grained and massive, with no visible cleavage. It appears water-worn and smoothly rounded.

Identified September 16, 2026More sedimentary →

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At a glance

Common name: Rounded gray-green chert (likely silicified limestone)
Scientific name: Microcrystalline quartz/chalcedony (SiO₂), possibly jasper or siliceous limestone
Category: sedimentary
Identified: September 16, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common field-collected piece; $20–$100 if unusually patterned, polished, or demonstrably collectible.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Formed when silica replaced or cemented carbonate sediment, commonly during diagenesis; its exact geological age cannot be determined from the image. Later stream or shoreline transport produced the rounded shape.

Uses & applications

Common chert is used locally as aggregate, road material, landscaping stone, and historically for tools; attractive pieces may be polished as decorative objects. Typical specimens have modest value.

Geological facts

Chert commonly breaks with a curved, conchoidal fracture and can produce sharp edges. Green coloration may reflect chlorite, iron-poor minerals, or other trace impurities.

Field identification & locations

Identify it by its dense, lightweight-for-size feel, waxy surface, lack of visible grains, and ability to scratch ordinary glass; a steel file should leave little mark. Chert occurs widely in sedimentary formations and stream gravels worldwide.