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Geology/Can you help me identify this?


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I am in Lake City, MI around Lake Missaukee, a glacier lake.

On My walk this week I found a most interesting thing. I cannot identify it, and it is unlike any other rock I have collected.

Hi Deb,
You have a rather nice piece of petrified wood.  The striations you see on the sides are the exact replication of the actual bark of this limb/trunk.  The colorful interior is what's left over after all the organic material is replaced by silica.  

What happens is, wood gets buried for a long time and ground water, that happens to be rich in dissolved silica, flows around and saturates the wood.  Over time all the organic molecules get replaced by silica modules and you get agatized wood.   It's called "petrified" because it's been turned into a rock.

It's very cool, not only because it is what it is, but because it's pretty rare to find petrified wood in Michigan.  It happens, but not often and yours is a nice sized specimen.  Very nice indeed.  

Here's some pics of petrified wood that look a bit like yours;

One final thing; sometimes the replacement of molecules can be so exact that a wood expert can actually tell what kind of tree it was when alive.  I'd take it to a college where a horticulturist can look at it.  Maybe even an expert in a large garden shop could help.

Hope this helps.


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C. Robert Reszka, Jr.


I can answer any general geology question (rocks, minerals, stratigraphy, geomorphology etc.). My expertise is in the geology of the Michigan Basin, PreCambrian, Paleozoic and Recent. I can answer questions concerning mining and petroleum exploration and production and the laws concerning those activities. I can also answer questions concerning stratigraphy of the Michigan Basin. I will also answer questions about mineral and rock collecting in the Basin. I won`t be able to answer many specific questions on hydrology, geophysics or geochemistry. I may be able to answer very general questions in those venues.


I have been working for the State of Michigan for 36 years as a Geologist and a Resource Analyst. I have experience with Subsurface Geology and Petroleum Geology, mining in Michigan, and Sand Dune Mining and Protection issues.

Michigan Basin Geological Society

Decade of North American Geology.
Bedrock Geology of Michigan

BS Wayne State University

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