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Mottled

Rockwood

By Rockwood
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abyssunder Regular Member

abyssunder

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In my thought, it could be igneous rock, maybe porphyritic with phenocrysts.

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" We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. "

Thomas Mann

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fossilcrazy Regular Member

fossilcrazy

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I encounter shale that looks just like that a Red Hill site in Pennsylvania. In the rock the mottled Reddish brown shale and Greenish grey shale are from changes in the rock chemistry in lithification.

Organic matter can reduce the Iron content from Ferric oxidation state (Fe +++) to Ferrous oxidation state (Fe ++). The two colors of each Iron Oxide state, corresponds to the Red and Green. I am fairly sure that is what is going on in your rock specimen. 

hyner scale.jpg

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Rockwood Regular Member

Rockwood

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Might one think of it as a fossiloid ? Or is there seriously a term which describes situations like this ?

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