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Post by nichwhitt on May 13, 2012 21:41:42 GMT -5
Found a couple of these...this one is white with a pinkish undertone on the nodules. The other one I found has light blue undertone. Theres a third one, but it looks more like a shelf mushroom. Anyone seen anything like it? Its not brittle or powdery...its actually quite hard. Attachments:
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Post by rockshine on May 14, 2012 5:43:46 GMT -5
I think it started out as a sedimentary/limestone, that weathered/etched during periods of shallow sea and alternate periods of uplift, with lithification (learned a new word yesterday) ( that's how you "fossilize" a porous rock that is already a rock). ( Fossilization is making a rock replacement out of organic material). And that is my run on sentence for the WEEK, complete with triple parentheses.
In other words, SiO2 (quartz) replaced the lime, forming the agate/jasper/ etc you will find when you open the stone.
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Post by raleighrocks on May 14, 2012 11:03:39 GMT -5
So its a geode?
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Post by kap on May 14, 2012 12:41:41 GMT -5
If its hollow a geode if solid a nodule. Open it up and see  Keith |
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Post by justarock on May 14, 2012 16:57:47 GMT -5
I have found some like that, with the pink undertones. Thought they were just conglomerates. Some have small geodes. They are hard enough to take a polish, the different minerals that make it up make for interesting designs. Some are fractured, most time they will come apart while cutting.
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Post by raleighrocks on May 14, 2012 21:39:23 GMT -5
thanks for the explanation Kap.
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Post by nichwhitt on May 18, 2012 6:41:57 GMT -5
I was hoping it was something like that. Once I get a setup, I'll "open it up", heh. Is there a dremel cut off wheel big enough to cut open some of these smaller rocks?
Also it seems too heavy to be a geode, so I'm betting on nodule. Great information here, guys, and that run-on was glorious, rockshine:D
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Post by nichwhitt on May 19, 2012 6:31:45 GMT -5
This 15 pounder has some similar qualities, however the shell is powdery. I'm guessing its quartz based because I have been using it to smash other hard rocks. I hope I'm not fracturing something really nice in there! Attachments:
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Post by leonardo on May 19, 2012 16:11:27 GMT -5
I did not know there were that many different type of rocks in MN.
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Post by nichwhitt on May 20, 2012 19:50:52 GMT -5
Me neither...the lake, you can walk out forever, then it drops to 80 ft deep. It either was cratered or a glacier took a big ass chunk out of the ground. I think thats why I am finding such a variety...
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