sedimentary

Likely polished stromatolitic chert or jasper pebble

Silicified microbialite (microcrystalline quartz, SiO₂); identification is provisional from the photo

AI-generated identification · may be incorrect

Opaque, rounded brown-and-dark-blue specimen with mottled patches; likely Mohs 6.5–7, vitreous to dull luster, and no visible cleavage. Fine-grained quartz makes crystal structure indistinguishable without magnification.

Identified October 4, 2026More sedimentary →

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At a glance

Common name: Likely polished stromatolitic chert or jasper pebble
Scientific name: Silicified microbialite (microcrystalline quartz, SiO₂); identification is provisional from the photo
Category: sedimentary
Identified: October 4, 2026
Method: Standard

AI Estimated Value

About $2–$20 for a small, common polished pebble; unusual patterns or verified provenance may raise value.

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

If stromatolitic, it formed as microbial mats trapped sediment in shallow water, later silicified; such rocks span much of geological time. The image alone cannot establish its exact age or formation.

Uses & applications

Polished examples are mainly collected or used as decorative stones; jasper and chert also have histories as tools and ornamental materials.

Geological facts

The contrasting colors may reflect iron oxides and other impurities, but the pattern is not diagnostic in this photograph.

Field identification & locations

Look for consistent fine-grained silica texture and hardness sufficient to scratch glass; confirm with close inspection or mineral testing, since the pictured pattern could fit several rocks. Chert and jasper occur worldwide.