Fossil Fish
Image: Gary Todd (CC0)
Mineral NameFossil Fish
Chemical FormulaCaCO3, SiO2 (fossil replacement); various silicates (matrix)
Mohs Hardness3.5
Streak ColorWhite to dark gray
CleavageNone (fossil), poor platy (matrix)
FractureUneven to conchoidal
Specific Gravity2.4
Colorslight gray, beige, dark gray, black
TransparencyOpaque
Type LocalityMongolia
Mineral GroupFossil (biogenic/sedimentary)
Usesscientific study, museum display, educational purposes, collector's item
Associated Mineralscalcite, quartz, clay minerals, carbonaceous material
Description
A well-preserved fossil of a fish, likely Lycoptera, showing detailed skeletal structure in dark gray to black, embedded in a light gray to beige sedimentary rock matrix.
Geological Context
Formed through the rapid burial of a freshwater fish in fine-grained sediments (like mud or silt) in ancient lake environments, leading to permineralization or carbonization of the organic remains over millions of years, typically from Mesozoic lacustrine deposits.
