Ooid
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Ooids are small, spheroidal, "coated" sedimentary grains, usually composed of calcium carbonate, but sometimes made up of iron- or phosphate-based minerals. Ooids usually form on the sea floor, most c
Modern ooids from a beach on Joulter Cays, The Bahamas.
Ooids on the surface of limestone; Carmel Formation (Middle Jurassic) of southern Utah, USA.
A thin slice of calcitic ooids from the Carmel Formation, Middle Jurassic, of southern Utah, USA.
Fossils ooimmured in ooids from the Carmel Formation (Middle Jurassic of southern Utah).
Iron-rich sedimentary rocks
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Iron-rich sedimentary rocks are sedimentary rocks which contain 15 wt.% or more iron. However, most sedimentary rocks contain iron in varying degrees. The majority of these rocks were deposited during
Iron ore from Kryvyi Rih, Ukraine.
Bog ore from Poland
Banded iron formation close up, Upper Michigan.
Superior type banded iron formation, North America.