GeologyRocksNeed help identifying
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links for photographs
Tue, 06/14/2011 - 22:33it looks like the photos did not make it, so here the links
http://i258.photobucket.com/albums/hh250/clbankst/DSCF2935.jpg
http://i258.photobucket.com/albums/hh250/clbankst/DSCF2940.jpg
http://i258.photobucket.com/albums/hh250/clbankst/DSCF2943.jpg
http://i258.photobucket.com/albums/hh250/clbankst/DSCF2937.jpg
http://i258.photobucket.com/albums/hh250/clbankst/DSCF2938.jpg
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Hi clbankst, Welcome to GR!
Thu, 06/16/2011 - 17:36Hi clbankst,
Welcome to GR! It looks like a flint nodule to me:
"The exact mode of formation of flint is not yet clear but it is thought that it occurs as a result of chemical changes in compressed sedimentary rock formations, during the process of diagenesis. One hypothesis is that a gelatinous material fills cavities in the sediment, such as holes bored by crustaceans or molluscs and that this becomes silicified. This theory certainly explains the complex shapes of flint nodules that are found. The source of dissolved silica in the porous media could arise from the spicules of silicious sponges. Certain types of flint, such as that from the south coast of England, contains trapped fossilised marine flora. Pieces of coral and vegetation have been found preserved like amber inside the flint. Thin slices of the stone often reveal this effect."
From the following: http://en.wikipedia.org/wiki/Flint
This is just a best guess, so don't take it as gospel. I'm sure someone else will correct me if they think otherwise!
Regards,
Ben.
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Flint Rock
Fri, 06/17/2011 - 00:18Clbankst,
I agree with Benauld.... Flint rock can usually be found in areas where there is new construction or an area where erosion has occurred. Flint is considered hard and has a tendency to split into pieces. Flint rock often is dark gray, but it can also be yellow, red or brown like the photo you provided.
Allan
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Need help identifying
Submitted by clbankst on Tue, 06/14/2011 - 22:23.We were doing a little geocaching in Plano, Texas a few years back and came across this odd rock along a creek. I have been meaning to return to look for other pieces, since it shouldn't be too hard to spot since everything else around is limestone. The rock is about the size of a walnut and is slightly magnetic. You can see what appears to be iron embedded in the stone. It weighs about 37 grams. It sits on my desk and my students ask me all the time what type of rock it is, so it would be nice to be able to provide a proper answer besides, "I'm not sure." I would appreciate any information about it. Thanks for you time.