Oolite

A oolite or oolite (of the Greek ôon meaning egg and lithographies meaning stone) is a regular spherical mineral structure (Ooïde), organized roll some concentric, of a size ranging between 0,5 and 2 Misters.

An oolite is made up of a core (nucleus) around whose was initiated the concentric development. It is of a Bioclaste (remains of biological origin) or about a Lithoclaste (remains of rock). Around the core develops roll them (cortex), inces often superimposed layers limestones and sometimes rugineuses Fer. The oolites are formed in not very major but agitated seamen circle. They remain in permanent suspension, while the layers forming the cortex are set up; when they become too heavy, they settle on sea-bed and form a deposit.

The purely mineral origin of the oolites is prone to debate in the community of the sedimentologists. The oolites current present a bacterial microphone-filament surfaces some, which could help with carbonated precipitation. It would be then about induced precipitation (in opposition to a controlled precipitation, like in the case of the tests of marine animals), on the model of the Stromatolithe S.

The iron ore of Lorraine is a ferruginous Minerai of Fer composed of oolites.

The oolite term was also employed to indicate stratigraphic layers formed by these small concretions. This meaning of the term is not used any more, and one speaks about rocks with oolites.

One often opposes to the oolites the oncolithes, classified among the Oncoïde S (irregular structures).

See too

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