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Fossiliferous limestone & kukersite (Viivikonna Formation, Middle Ordovician; Kohtla-Järve, Estonia) - Fossiliferous limestone from the Ordovician of Estonia.
The light gray material seen here is fossiliferous limestone, a biogenic sedimentary composed of calcite (CaCO3 - calcium carbonate). The brown material is kukersite, a variety of oil shale (although lithologically, this is not oil shale). Kukersite is a hydrocarbon-rich sedimentary rock that burns in a fire. Upon heating, kukersite releases petroleum.
Stratigraphy: "Estonia Deposit", Kiviõli Member, Viivikonna Formation, Kukruse Stage, Middle Ordovician (sensu traditio)
Locality: unrecorded/undisclosed site at or near the town of Kohtla-Järve, northeastern Estonia
See info. at:
en.wikipedia.org/wiki/Kukersite
