Need help with I.D.

[SammyJ]

Novice warning!!!
I have been slowly scraping away the clay from around these and I don't know what they are. I was thinking maybe Pyrite crystals. This is a plate of clay about 6 or 7 inches long, 2 inches thick with a quartz vein through the middle. These crystals are sitting above the quartz line in the clay layer. They seem to be a dirty reddish colour under a light and there are more I have uncovered since the photo was taken.
How would I polish these to see what they are?

 

[kawman]

break one open mate.. they do look a bit like pirite cyrstals :/

 

[SammyJ]

break one open mate.. they do look a bit like pirite cyrstals :/

I'm torn as I would like to keep them on matrix as a display piece.

 

[kawman]

I am hearing that and you are correct that it will make a nice specimen indeed.. not sure how to clean the pirite if it is because it is not very robust and will damage very easy.. :/

 

[blisters]

Acid of some kind, by the sounds of the colour you have oxidised pyrite. I'd start with vinegar but you might have to move onto other acids if not effective. I think oxalic acid is used for a variety of mineral cleaning which will probably dissolve away the host rock if ferruginous. You could make a paste using vinegar and flour to start just do it on one cube first just in case. I had a chat to a guy at one of those gem shows and he told me how to do it but unfortunately I can't remember the cleaning bit, but once clean you can stick and coat things together with a very diluted mix of wood glue and water (unless he was pulling my leg).
Jon

 

[Lefty]

I've found similar perfectly shaped little crystals like that in gold-bearing country. They were a pseudomorph - hematite after pyrite, where the pyrite crystals have been replaced by hematite that has assumed their form. If you can bear to sacrifice one just a little to determine wether or not it is actually pyrite under the coating, hematite will leave a brownish-red to cherry red streak on unglazed porcelain.

 

[SammyJ]

Thanks for the help! I'll keep at it and see how I go. It is from Beaufort. So definitely gold bearing country.

 

[blisters]

... They were a pseudomorph - hematite after pyrite...

Yeah I forgot about that, the old brain is getting rusty itself :lol:
Jon

 

[shivan]

Could be a Pyrite or galena, but the colour makes it sound more like what Lefty said, a pseudomorph like hematite or possibly limonite.

If you want to keep them in the clay matrix, try starting off with hot soapy water a toothbrush (kids ones are nice and small). Then maybe try a cotton bud and vinegar or the trick blisters suggested. If its pyrite oxalic acid would make them shine, but you need to soak them, and i don't think it would do the clay any good.

 

[LONEWOLF]

To clean Pyrite ...a 50g/L ( i.e.5%w/v) solution of Citric Acid..... Soak for a few minutes and you have a nice shine on your Pyrites... You can get Citric Acid from the cooking section of your local Supermarket.... this may help...

LoneWolf.....

 

[Westaus]

I've found similar perfectly shaped little crystals like that in gold-bearing country. They were a pseudomorph - hematite after pyrite, where the pyrite crystals have been replaced by hematite that has assumed their form. If you can bear to sacrifice one just a little to determine wether or not it is actually pyrite under the coating, hematite will leave a brownish-red to cherry red streak on unglazed porcelain.

This was my first thoughts as well.

https://www.google.com.au/search?q=...AGwQ_AUIBigB#tbm=isch&q=limonite+pseudomorphs

 

[SammyJ]

I've found similar perfectly shaped little crystals like that in gold-bearing country. They were a pseudomorph - hematite after pyrite, where the pyrite crystals have been replaced by hematite that has assumed their form. If you can bear to sacrifice one just a little to determine wether or not it is actually pyrite under the coating, hematite will leave a brownish-red to cherry red streak on unglazed porcelain.

This was my first thoughts as well.

https://www.google.com.au/search?q=...AGwQ_AUIBigB#tbm=isch&q=limonite+pseudomorphs

Thanks for the link Westaus. That's it. identical. Now I know why I cant get a shine on them. Thank you for your help.