Orthoceras Fossil
Image: “Jon Zander (<a href="//commons.wikimedia.org/wiki/User:Digon3" title="User:Digon3">Digon3</a>)" (CC BY-SA 3.0)
Mineral NameOrthoceras Fossil
Chemical FormulaCaCO3
Mohs Hardness3
Crystal Systemtrigonal
Streak Colorwhite
Cleavageperfect rhombohedral
Fractureconchoidal to uneven
Specific Gravity2.71
Colorswhite, light grey, dark grey, black
Transparencyopaque
Type LocalityWorldwide in Silurian marine deposits (e.g., Morocco, Baltic region)
Mineral GroupCarbonates
Usescollector's item, decorative object, educational specimen
Associated Mineralscalcite, limestone, shale, dolomite
Raritycommon
Description
This specimen displays an elongated, conical Orthoceras shell, light grey to white with distinct dark septa, embedded longitudinally within a dark grey to black sedimentary rock matrix.
Geological Context
Orthoceras fossils are the preserved remains of extinct nautiloid cephalopods that inhabited ancient marine environments during the Silurian period, typically found in sedimentary rocks like limestone.
