sedimentary

Stromatolite (Jasper-replaced)

Fossilized Stromatolite (Cyanobacteria / Cryptozon / Silica SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Shades of green, grey, and cream; Luster: Waxy to vitreous when polished; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65.

Hardness: 6
Color: Shades of green, grey, and cream
Luster: Waxy to vitreous when polished

Identified March 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the layering of ancient cyanobacteria (blue-green algae) trapping sediment in shallow marine environments. Over billions of years, the organic structures are replaced by silica. These specific specimens often date back to the Proterozoic or Archean eons (approx. 2 billion years old).

Uses & applications

Primarily used as decorative stones, lapidary material for jewelry (cabochons), and as educational fossils for collectors.

Geological facts

Stromatolites are the oldest fossils on Earth and are responsible for the 'Great Oxygenation Event,' which created the oxygen-rich atmosphere that allowed complex life to evolve.

Field identification & locations

Identify by the characteristic 'onion-skin' or wavy concentric banding and its high hardness (won't be scratched by steel). Commonly found in the Mary Ellen Iron Formation (Minnesota) and Western Australia.