Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: lukasjacobs on 19/10/2015 21:59:49

Title: What is this small black piece of stone?
Post by: lukasjacobs on 19/10/2015 21:59:49

please id this.

Title: Re: What is this small black piece of stone?
Post by: RD on 20/10/2015 01:28:37

Magnetite (https://commons.wikimedia.org/wiki/File:Magnetite-146684.jpg) ?

Title: Re: What is this small black piece of stone?
Post by: lukasjacobs on 20/10/2015 04:52:46

It is non magnetic.Have not been cut etc. in any way.It looks like red sand in between the crystals,acid in lab could not clean it up.v

Title: Re: What is this small black piece of stone?
Post by: chris on 21/10/2015 11:30:52

It's certainly fascinating, although I don't know what it is; can you tell us a bit more about the context in which it was found?

Title: Re: What is this small black piece of stone?
Post by: Bass on 24/10/2015 19:46:05

Cubic form of the crystals indicates this is a pyrite nodule. I assume it feels a bit heavier than a regular garden stone of the same size.  Black color is probably goethite oxidizing from the pyrite.

Title: Re: What is this small black piece of stone?
Post by: Bill S on 25/10/2015 17:52:25

Have you tried scratching a crystal to check the colour of the streak?

Title: Re: What is this small black piece of stone?
Post by: chris on 25/10/2015 22:04:59

Quote from: Bass on 24/10/2015 19:46:05

this is a pyrite nodule.

What does this mean it's made of? Is it an iron sulphide?

Title: Re: What is this small black piece of stone?
Post by: Bass on 03/11/2015 23:17:07

Yes, iron sulfide (FeS2)

Title: Re: What is this small black piece of stone?
Post by: chiralSPO on 04/11/2015 03:30:45

I'm pretty sure it's a Borg Sphere, you might want to be careful with it if you don't want to get assimilated...

http://employees.csbsju.edu/rsorensen/modelcitizen/trekships/borg/borgsphere.jpg