File:Polished Quartz Nodule Grinder 01.jpg
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English: This puzzling sample is a naturally polished quartz nodule, dimensioned from 2 to 3 inches (about 50 mm, give or take). The surface porosity reflects the jointing of the underlying quartz crystals, generally less than 1 mm thick, that radiate from the inner core.
This piece was naturally ground from a quartz infill of a arthropod burrow (a trace fossil) common and peculiar to the Cottonwood Limestone ( see unpolished quartz nodule example in the gallery ). It was polished as a pothole grinder in a desolution chamber of the Cottonwood (see explanation of pothole grinders in this external link). Unfortunately, Wikipedia does not yet have an adequate article on this type of pothole formation. This grinder could have been active as the Kansas River cut through the formation; but as it was found in an excavation of the Cottonwood outcrop, a few hundred feet above the present river, it is very possible that this was polished by wave action of the glacial Pleistocene epoch Kaw Lake (Kansas) (article pending). |
| Date | |
| Source | Own work |
| Author | IveGoneAway |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 22:59, 26 November 2016 | | 1,865 × 1,499 (397 KB) | IveGoneAway (talk | contribs) | User created page with UploadWizard |
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