Friday mystery object #36 answer

Crumbs – rather inundated with comments about last Friday’s mystery object! Apologies for not answering all of the questions, the sudden leap in comments coincided with a particularly hectic day where I had virtually no computer access. The comments were wide ranging, from cannonballs to turtle eggs, truffles to coprolites (fossil dung), burnt cooking/toys to a bezoar. One of my favourites was the fossilised fist of a wood elf – and I can sort of see the similarity:

However, I am almost sad to say that it is none of the above. There were a few answers that came close, Don C suggested a concretion, Solius suggested mineral crystals, SmallCasserole identified that it was mineralised with a radial pattern, but one person had this hammered – Jeremy was spot on with with an identification of marcasite.

David Waterhouse from Norwich Castle Museum provided me with this description of the object:

this is a nodule of the mineral Marcasite (FeS2) closely related to Pyrite.  It was found on the ground in Thetford Forest about 20 years ago.  The whitish stuff you can see is chalk (marcasite sometimes forms from iron minerals within the Upper Chalk).  When fresh, this would have had a bright metallic lustre, but it has been exposed at the surface for many years and has dulled to the colour you see in the pictures.  Its orthorhombic crystal structure is difficult to see because of the weathering that has occurred.  It is heavy because of the iron in it, but not as heavy and less stable than pyrite.

So thanks to everyone who left comments – who knows, they may inspire future mystery objects. I’d better get looking for this week’s mystery object!

5 thoughts on “Friday mystery object #36 answer

  1. Rock on! 🙂
    I had to dig some way back in my memory to confirm that you could get marcassite on chalkland (you can see the chalk on the nodule, after all). Then I recalled finding it on the Isle of Wight preserving alleged urchin tunnels (of course you also find it lower down the sequence amongst the carbonised wood of the Jurassic).
    Looking forward to Friday again, Paulo. Assuming you don’t regard it as a holiday 😉

  2. Love the detail on the ‘fossilised wood elf fist’. Is this a carving or photoshopping of your own hand? If the former it is very fine indeed.

      • Yes, I thought it was your hand. There is quite a lot of variability in hands but this is almost identical to my own except the length of the thumb in proportion to the fingers. Even the lines look very similar .. explain that fortune tellers! … must compare properly next time I see you.

        “You have your mother’s hands” sounds like something one of Terry Pratchett’s Igors would say.

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