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Shuo Wang

Color of Russian trilobites

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Shuo Wang

Why are trilobites brown from Russia and black from other countries? What's the difference of the mineral composition between a brown trilobite and a black one? Both the trilobite fossil and the matrix are stones, why are their colors so different?

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Fossildude19

It is dependent on the minerals that were present in the sediments and water during the fossilization process. 

There are many brown trilobites from the US and Canada. I've found black, white, grey, and brown trilobites in the Middle Devonian of New York State.

I'm sure  @doushantuo probably has some taphonomic papers that address this question.

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Raggedy Man

The chemical make up of the sediments contribute to the fossil. If iron is present it may give the rock a reddish color. Phosphates may darken the rock to gray or black. The trilobites I find in the Upper Mississippi Valley also have the brownish caramel color as well. As Tim stated, they're not endemic to just Russia. 

 

For example

20180403_165837.thumb.jpg.e87dccc640b9dfe71807d6fd5558877e.jpg

 

These cephalons and bits are the brownish caramel color in question. They're from Indiana The Waldron shale and are silurian. 

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Shuo Wang
41 minutes ago, Fossildude19 said:

It is dependent on the minerals that were present in the sediments and water during the fossilization process. 

There are many brown trilobites from the US and Canada. I've found black, white, grey, and brown trilobites in the Middle Devonian of New York State.

I'm sure  @doushantuo probably has some taphonomic papers that address this question.

Thanks for your explanation.

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Shuo Wang
21 minutes ago, Raggedy Man said:

The chemical make up of the sediments contribute to the fossil. If iron is present it may give the rock a reddish color. Phosphates may darken the rock to gray or black. The trilobites I find in the Upper Mississippi Valley also have the brownish caramel color as well. As Tim stated, they're not endemic to just Russia. 

It turns out that iron is the "brownish ingredient". Thanks a lot for your answer!

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Shuo Wang
1 hour ago, Raggedy Man said:

The chemical make up of the sediments contribute to the fossil. If iron is present it may give the rock a reddish color. Phosphates may darken the rock to gray or black. The trilobites I find in the Upper Mississippi Valley also have the brownish caramel color as well. As Tim stated, they're not endemic to just Russia. 

 

For example

20180403_165837.thumb.jpg.e87dccc640b9dfe71807d6fd5558877e.jpg

 

These cephalons and bits are the brownish caramel color in question. They're from Indiana The Waldron shale and are silurian. 

If iron was present during the fossilization process, why is only trilobite brown? It looks like brownish trilobites are usually with white or gray matrix stones.

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Kane

This bumps up against the question of biochromes (organic pigments) and sclerochromes (colours associated with structure). It sounds like a trip to the library may be in your future!

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Shuo Wang
1 hour ago, Kane said:

This bumps up against the question of biochromes (organic pigments) and sclerochromes (colours associated with structure). It sounds like a trip to the library may be in your future!

It seems to be a complicated issue.

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ynot

There are other elements that can cause black or brown colors besides iron.

You can also have combinations of trace elements that will affect the color of a fossil.

It is a very complex subject.

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