File:Flint-knapped spearpoint (Burlington Formation, Mississippian) 5.jpg
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| Description |
English: (~15.6 centimeters tall) (Knapper: Adam Reynolds)
"Flint" is sometimes used as a lithologic term by modern geologists, but it is a synonym for chert. Flint and chert are the same - they are cryptocrystalline, quartzose sedimentary rocks. Rockhounds often assert that flint is high-quality while chert is low-quality. Some geologists assert that "flint" implies a biogenic origin and "chert" implies a chemical origin. Many cherts do have a chemical origin - chert nodules are moderately common in some limestone units. The nodules form during diagenesis - pre-existing silica components in the carbonate sediments are dissolved, mobilized, and reprecipitated as chert masses. Some cherts do have a biogenic origin - for example, radiolarian cherts (rich in radiolarian microfossils) or spicular cherts (rich in siliceous sponge spicules). Seen here is a knapped spearpoint - it's a modern replica. The rock is "Burlington Chert", derived from a nodule in the limestone-dominated Burlington Formation. The chert has been heat-treated to make it more knappable. Heating can also change the colors to the light pinkish-orangish present in this specimen. Stratigraphy: Burlington Formation, Mississippian Locality: unrecorded/undisclosed site in midwestern America |
| Date | |
| Source | https://www.flickr.com/photos/47445767@N05/51430606996/ |
| Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/51430606996. It was reviewed on 7 September 2021 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 14:40, 7 September 2021 | | 1,262 × 3,586 (2.39 MB) | Ser Amantio di Nicolao (talk | contribs) | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/51430606996/ with UploadWizard |
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