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Jackalope122

Can someone shed some light on this object?

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Jackalope122

Hello, I was hoping someone more experienced could shed some light on whether this object is anything of interest or if it's something man-made like a bead that happens to look like a natural formation. It was found in Rockford, IA at the fossil quarry, so Devonian if it's actually something fossilized. Is it possible it's a mineral formation of some kind? It's roughly 4mm x 4mm and non-magnetic. It seems to be well embedded in the rock. Thanks for your time!

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Bone guy

thats a beautiful little gem. Probably not fossil, but a really cool geological piece! Also welcome to the forum. :)  

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Jackalope122

Thanks for the help, and the welcome! I appreciate it!

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Fruitbat

I agree with FossilDAWG...looks like a garnet to me too!  Very NICE!  The only thing that bothers me is that you say it is non-magnetic.  Did you use a STRONG magnet or just a simple household magnet?

 

-Joe

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Jackalope122

I have a 150lb pull retrieval magnet from harbor freight and it shows no signs of attraction that I can see. Should it if it were a garnet? I only checked in the first place because of the rust color, I had no idea garnets should be magnetic. I'm not well versed in geology, as you can probably tell lol 

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Jackalope122

Very cool, thanks!

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Fruitbat

Garnets generally ARE metamorphic, which implies high temperature and pressure as DPS Ammonite says...but don't know about the condition of the fossils in your quarry because I don't SEE any fossils!  If it was pyrite (FeS2), I would certainly expect it to be attracted by a strong magnet!  I have never personally seen pyrite with crystals shaped like that (they are usually cuboidal or a variation on that theme) but I did read somewhere that pyrite can form dodecahedral crystals under certain circumstances.  And no...not all garnets are attracted to magnets!

 

-Joe

 

 

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Jackalope122

 

49 minutes ago, Fruitbat said:

Garnets generally ARE metamorphic, which implies high temperature and pressure as DPS Ammonite says...but don't know about the condition of the fossils in your quarry because I don't SEE any fossils!  If it was pyrite (FeS2), I would certainly expect it to be attracted by a strong magnet!  I have never personally seen pyrite with crystals shaped like that (they are usually cuboidal or a variation on that theme) but I did read somewhere that pyrite can form dodecahedral crystals under certain circumstances.  And no...not all garnets are attracted to magnets!

 

-Joe

 

 

The fossils at the Rockford fossil quarry are generally well preserved, at least in my limited experience. Thanks everyone for taking the time to comment, I really appreciate it!

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Pemphix

No garnet imo.

It's oxydized pyrite (therefore non-magnetic) grown as interpenetration twin - i think it is Kuboktaeder, Combination of {100} and {111} see for example here:

https://de.wikipedia.org/wiki/Pyrit

 

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elcoincoin

garnet imo, oxyded garnet, theones we have here in britanny (and we have a lot) nearly always have that brownish aspect due to oxydation.

 

like those for instance : 3237463771_1_9_ugWVqIm8.jpg

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WhodamanHD

I’m also in the limonite (or other iron oxide) camp. Is a wierd shape though, wonder if it replaced a crystal of some sort, kinda like how pyrite replaces asbestos in tigers eye but with a different mineral.

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ynot
2 hours ago, elcoincoin said:

, oxyded garnet, theones we have here in britanny (and we have a lot) nearly always have that brownish aspect due to oxydation.

Garnets do not oxidize. They can be a dark brown / rust color, but that is from the elemental traces in the structure.

They also take a lot of heat and pressure to form, which is not found in sedimentary rock.

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Plax

DPS ammonite has it right in my opinion.

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FossilDAWG

I'm fine with some variety of pyrite.  I suggested maybe garnet because of the crystal shape, but I did say tests would be needed to ID the mineral conclusively.  I don't know the geology of the Rockford quarry, but I have collected at limestone quarries (such as the ones around Montreal) where igneous dikes and sills are present and contain a spectacular array of unusual minerals.

 

Don

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Tidgy's Dad

If it's in limestone, and it appears to be, then +1 for oxidized pyrite. 

It's a nice piece, very interesting! :)

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