sedimentary
Stromatolite
Biogenic Sedimentary Rock (Precambrian Stromatolite fossil)
Hardness: 3-5 (Mohs), though can be higher if silicified; Color: Brown, tan, red, or gray; Luster: Dull to earthy; Structure: Layered or laminated 'cabbage-like' or wavy microbial mats.
- Hardness
- 3-5 (Mohs), though can be higher if silicified
- Color
- Brown, tan, red, or gray
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-5 (Mohs), though can be higher if silicified; Color: Brown, tan, red, or gray; Luster: Dull to earthy; Structure: Layered or laminated 'cabbage-like' or wavy microbial mats.
Formation & geological history
Formed by the growth of layer upon layer of cyanobacteria (blue-green algae) in shallow water, trapping and binding sediment. These date back to the Precambrian, often over 2.4 to 3.5 billion years old.
Uses & applications
Used primarily for geological research, education, and as a collector's specimen. Polished pieces are used in decorative items and jewelry.
Geological facts
Stromatolites are some of the oldest records of life on Earth. They were responsible for creating the oxygen-rich atmosphere we breathe today through photosynthesis.
Field identification & locations
Identify by distinct concentric or wavy 'rib' layers. Commonly found in areas with ancient seabed exposure like the Great Lakes region or Glacier National Park.
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