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Steve Cole
Joined: 18 Aug 2017
Posts: 2
Location: Redhill
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Posted: Aug 18, 2017 14:21 Post subject: Can you identify this 'hedgehog'? |
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Found on the 'South Downs' in Southern England, this is very different to the usual chalk and flint in that area. It is 5cm across, rather heavy, not influenced by a magnet, and covered in triangular crystals. It cannot be easily scratched by a pocket knife.
Locality: | Fulking, Mid Sussex District, West Sussex, England / United Kingdom | |
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Dimensions: | 5cm |
Description: |
Fulking Down, West Sussex Compared with a UK £1 coin. |
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kushmeja
Joined: 28 Jul 2014
Posts: 244
Location: New Jersey
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Posted: Aug 18, 2017 14:37 Post subject: Re: Can you identify this 'hedgehog'? |
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Based on it's appearance and the minerals in that area, I'd say that it's pyrite that was partially altered to limonite. Mindat has pics of a pyrite nodule in flint that was found in West Sussex that looks very similar, but not altered to limonite.
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Peter Megaw
Site Admin
Joined: 13 Jan 2007
Posts: 963
Location: Tucson, Arizona
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Posted: Aug 18, 2017 14:39 Post subject: Re: Can you identify this 'hedgehog'? |
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Looks like a partially oxidized marcasite nodule from a sedimentary formation. It probably smell sulfurous if you take a whiff.
It will almost certainly continue oxidizing and eventually fall apart. You might be able to slow that down by washing with 90% isopropyl alcohol to kill the bacteria that hasten the oxidation. Scrubbing with a toothbrush to remove the rusty oxidation may reveal some of the golden metallic color of the marcasite.
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Joseph DOliveira
Joined: 29 Jan 2012
Posts: 299
Location: Hanmer, Ontario
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Posted: Aug 18, 2017 15:26 Post subject: Re: Can you identify this 'hedgehog'? |
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I'm with Peter on marcasite, very similar to the marcasite nodules from the Belle Fourche Reservoir in South Dakota. If you're looking to clean them up and remove the oxidation, a light blasting with a sand blaster and glass beads will do nicely.
Peter Megaw wrote: | Looks like a partially oxidized marcasite nodule from a sedimentary formation. It probably smell sulfurous if you take a whiff.
It will almost certainly continue oxidizing and eventually fall apart. You might be able to slow that down by washing with 90% isopropyl alcohol to kill the bacteria that hasten the oxidation. Scrubbing with a toothbrush to remove the rusty oxidation may reveal some of the golden metallic color of the marcasite. |
_________________ Joseph D'Oliveira
Hanmer, Ontario
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Steve Cole
Joined: 18 Aug 2017
Posts: 2
Location: Redhill
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Posted: Aug 18, 2017 16:29 Post subject: Re: Can you identify this 'hedgehog'? |
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kushmeja wrote: | Based on it's appearance and the minerals in that area, I'd say that it's pyrite that was partially altered to limonite. Mindat has pics of a pyrite nodule in flint that was found in West Sussex that looks very similar, but not altered to limonite. |
Are you able to give me a link to the Mindat pictures? Thanks!
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Aug 18, 2017 22:32 Post subject: Re: Can you identify this 'hedgehog'? |
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Hi,
Yes, a marcasite nodule. Radiating crystals.
These concretions are frequent in the north of France in farming areas. Dimensions up to 15 cm in diameter
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