sedimentary

Stromatolite

Stromatolite (Cyanobacteria-formed Organo-sedimentary structure)

AI-generated identification · may be incorrect

Hardness: 4-7 (varies by mineral enrichment); Color: Tan, brown, grey, or reddish; Luster: Dull to earthy; Structure: Laminated, wavy or mounded layers; SG: 2.6-2.8.

Hardness: 4-7 (varies by mineral enrichment)
Color: Tan, brown, grey, or reddish
Luster: Dull to earthy

Identified May 18, 2026More sedimentary →

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Physical properties

Hardness: 4-7 (varies by mineral enrichment); Color: Tan, brown, grey, or reddish; Luster: Dull to earthy; Structure: Laminated, wavy or mounded layers; SG: 2.6-2.8.

Formation & geological history

Formed by the trapping, binding, and cementation of sedimentary grains by biofilms (microbial mats) of microorganisms, specifically cyanobacteria. They date back over 3.5 billion years, making them among the oldest records of life on Earth.

Uses & applications

Used primarily for scientific research on early life, education, and as decorative lapidary material when silicified (polished fossil slabs).

Geological facts

Stromatolites provided the oxygen for Earth's atmosphere through photosynthesis. While most are ancient fossils, living stromatolites can still be found today in Shark Bay, Australia.

Field identification & locations

Identify by distinctive fine, concentric or wavy laminations (layering) that differ from standard sedimentary bedding. Often found in ancient limestone or dolostone formations.