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Showing results for tags 'freeze thaw'.
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I am new to the fossil collecting hobby and am attempting to open my iron concretions collected in Braidwood, IL using the freeze thaw method. I am doing it in my freezer in a single layer in a plastic shoe box. When they are thawing at room temperature the outer layers are crumbling. The nodes have not split yet. Is that normal or am I doing something wrong? Thanks.
Hi all, A couple of months ago, I acquired a small box of unopened Mazon Creek nodules via the forum. After reading whatever I could find on the freeze-thaw method (too many TFF topics to cite here), I started doing the following. First, I submerged the nodules in water (in 6 cm deep trays, fully submerging the nodules, which were placed next to each other, not stacking them) for one week (I was on vacation). Subsequently, I put the trays in freezer until frozen solid (1 day). I repeated these steps (duration 1 day each) until nodules popped open/could be opened by hand. Most of my nodules have opened by now (two to go still) and this is what I found: Some of the nodules seem to contain bits (e.g. the ones on lower right - any ID suggestions?), but most are empty, at least to my untrained eye (have zero previous experience with Mazon Creek material). I've read the "content" of the nodules varies from site to site, and general estimates range from 1/4 to 1/10 nodules yielding something fossiliferous. However, most others who obtained nodules from the same source reported nice finds in their batches. Given this, I was wondering whether I did something wrong method-wise. Also, is it worthwhile to re-split nodules, i.e. put them back in the freezer and try splitting them along a parallel plane? P.S. During the freeze-thaw cycling, many of the nodules started to "peel"; the outer parts started to disintegrate in somewhat onion-like fashion. Is this normal? Thanks for your input, Tim