fossil

Polished stromatolite (likely fossilized microbial mat)

Fossil stromatolite; chiefly microcrystalline quartz (SiO₂), commonly replacing carbonate

AI-generated identification · may be incorrect

Tan to golden-brown, fine-grained, satin-to-waxy luster with strongly contoured, concentric laminae; hardness about 6.5–7 if silicified, little or no cleavage, specific gravity roughly 2.6. The rounded shape indicates cutting and polishing.

Identified August 19, 2026More fossil →

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At a glance

Common name: Polished stromatolite (likely fossilized microbial mat)
Scientific name: Fossil stromatolite; chiefly microcrystalline quartz (SiO₂), commonly replacing carbonate
Category: fossil
Identified: August 19, 2026
Method: Standard

AI Estimated Value

About $10–$50 for a small polished piece; $50–$200+ for large, especially attractive or well-documented specimens.

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

Stromatolites formed when microbial communities, especially cyanobacteria, trapped and bound sediment in shallow marine or lake environments; silicification or carbonate lithification preserved the layers. Many commercial examples are Precambrian, commonly about 1.0–2.5 billion years old.

Uses & applications

Used as a lapidary, display, educational, and fossil-collecting material; occasionally made into cabochons and ornamental objects.

Geological facts

The banding records successive microbial growth surfaces rather than mineral crystal layering. Stromatolites are among Earth’s oldest macroscopic evidence of life.

Field identification & locations

Identify by irregular domed or wavy laminations, fine texture, and nonrepeating natural banding; acid testing may distinguish carbonate specimens, while a steel file should not readily scratch silicified material. Common sources include Western Australia, Bolivia, Morocco, and parts of North America.