Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: cren on 07/05/2014 00:27:08

Title: Can someone please help me identify this?
Post by: cren on 07/05/2014 00:27:08

I dug this up from my drive way a little while back. No one can seem to figure out what it is, I even took it to a local gem/rock/jewelry shop and they suggested asking a geologist. Its octahedral in shape. Its about the size of a marble and weighs about as much as a nickel. Can someone help me? I live in Ohio if that helps. Thanks! Please message if you need a better pic the forum only let me post this size.

Title: Re: Can someone please help me identify this?
Post by: Bass on 07/05/2014 17:51:13

My first impression is pyrite, which commonly forms octohedrons.  In the photo, the color appears to be close to bronze? Is there any iron oxide on the surface? Hardness?

Title: Re: Can someone please help me identify this?
Post by: cren on 07/05/2014 21:04:46

There is no iron oxide and its hard, almost like metal, but doesn't react to magnets. Hopefully this is a better pic of it. Thanks Bass!

Title: Re: Can someone please help me identify this?
Post by: Bill S on 07/05/2014 21:33:19

Hi Cren.  You say it's "...hard, almost like metal".  That tends to support Bass.  In my (limited) experience, cubes are much commoner than octohedrons, but that may be a local feature.  If it is pyrite, it will be hard to scratch, but if you can scratch it (with a piece of quartz, perhaps), the streak should be blackish, possibly with a greenish/brownish tinge. 

Title: Re: Can someone please help me identify this?
Post by: cren on 07/05/2014 23:26:53

Hi Bill, Thanks for the info! I used a piece of quartz to attempt to scratch it, but every time the quartz flaked off and dulled the points. However, there was a residue that was left behind and it was dark grey. The residue easily wiped off and there was no blemish on the octahedral. Does this mean it is most likely pyrite? I have pyrite and it looks nothing like it and when I googled pyrite non of the pics look like the material the octahedral is made of, but I'm no expert and I may not be seeing what you two are. Thanks again!

Title: Re: Can someone please help me identify this?
Post by: RD on 08/05/2014 08:57:51

+1 for pyrite. The surface of pyrite can "rust" rather than appear brassy (http://skywalker.cochise.edu/wellerr/crystals/isometric/6iso-pyrite4795.JPG)...

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Title: Re: Can someone please help me identify this?
Post by: cren on 08/05/2014 20:04:57

Thanks for the pic RD. I didnt think it was rust because it feels so smooth. I've never seen weathering create such drastic features on a rock like this and have only seen very sharp looking pyrite, but it totally makes sense if it was severely weathered and rusted to make the eye catching features so indented.  Thanks again!

Title: Re: Can someone please help me identify this?
Post by: Bass on 09/05/2014 00:32:44

My guess is still pyrite. Nice specimen

Title: Re: Can someone please help me identify this?
Post by: CliffordK on 09/05/2014 00:40:13

Quote from: cren on 07/05/2014 21:04:46

There is no iron oxide and its hard, almost like metal, but doesn't react to magnets.

Iron pyrite is not magnetic.  I've got a specimen around here somewhere.  I've tried a Neodymium magnet with it...  Nothing.  I believe it was non conductive too.  Your specimen does have a most unique texture.

Title: Re: Can someone please help me identify this?
Post by: cren on 09/05/2014 02:03:25

Thanks for all the help everyone...this weekend hopefully I can get a hold of a digital scale to find the specific gravity to confirm. I'll update as soon as I know.