Stromatolite
Indeterminate genus of Cyanobacteria (microbial mat association) • Trace fossil (Organosedimentary structure); Biogenic calcareous structure
Geological Period
Precambrian (ranging from Archean to Proterozoic)
Estimated Age
541 to 3,500 million years
Preservation Type
Recrystallization and replacement (usually carbonate or silica replacement); permineralization
Condition Assessment
Good; shows clear internal lamination and structural integrity, though weathered on the outer cortex
Taxonomic Classification
Phylum: Cyanobacteria (Microbialites); Form-family: Spongiostromata; Genus: cf. Collenia or Cryptozoon
Morphological Description
Exhibits diagnostic concentric, wavy, and laminated structures formed by the trapping and binding of sediment by microbial mats. Cross-section shows distinct 'cabbage-like' or domal accretionary layering with micro-porous textures.
Rock Matrix
Dolostone or Limestone matrix, often brownish-tan due to iron oxidation or dolomitization
Formation & Location
Possible Gunflint Chert (USA/Canada), Bitter Springs (Australia), or similar ancient carbonate platforms
Size & Dimensions
Approximately 5-8 cm in horizontal width; consistent with typical hand-sample colonies
Value & Rarity
Estimated Market Value
$25 - $60 USD
Auction Estimate
$40 - $80 USD
Rarity Assessment
Common in the geological record, though high-quality polished sections are selectively collected
Scientific Significance
Represents the earliest evidence of life on Earth; instrumental in the Great Oxygenation Event through photosynthetic processes
Preparation Recommendations
Diamond saw cut followed by high-grit polishing to reveal internal lamination details; store in a dry environment
Notable Features
Distinctive wavy laminae reflecting the daily growth cycles of ancient cyanobacterial mats; high contrast between darker and lighter mineral layers