pacchardon
off to a rocking start
Member since August 2015
Posts: 22
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Post by pacchardon on Aug 16, 2022 16:35:28 GMT -5
Can peacock ore (bornite) be tumbled? I see that it is pretty soft (Mohs 2.5 - 3.0). I picked up a couple of lbs. of it a few years ago and set it aside and forgot about it. Anyone have any experience with it?
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Post by vegasjames on Aug 16, 2022 18:09:36 GMT -5
Peacock ore is a name used for both bornite and chalcopyrite. Both produce an iridescent tarnish on the surface with oxidation.The tarnish is super thin and would be easily removed with tumbling. Although, it is possible to re-tarnish the stone as with acid treatment afterward. This is a common practice of artificially tarnishing bornite and chalcopyrite to enhance the colors for market. Naturally occurring bornite and chalcopyrite rarely have the really intense colorful tarnish you see with the stones sold in stores.
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lordsorril
freely admits to licking rocks
Member since April 2020
Posts: 766
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Post by lordsorril on Aug 17, 2022 12:15:56 GMT -5
I have tumbled and polished bornite and chalcopyrite, they are effectively the same IMO with material ID'd as bornite being a bit higher mohs. Produces a real nasty greyish green slurry in tumble which is capable of dying your skin if not washed off soon enough. The stones turn gold when the oxidative layer is removed. In my Snakes and Stones thread I used chalcopyrite/bornite in photos #2, 24, 106, and 155. Photo #2 also is emeralds, but, they are easy to tell apart. Snakes and Stones
If you have small pieces then start at #220 or #500 SiC in a 3lb. barrel. Soft material like this really needs a vibe to finish. My recommendation is to pick out the iridescent pieces you like (as I did below-old photo), and tumble the rest.
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pacchardon
off to a rocking start
Member since August 2015
Posts: 22
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Post by pacchardon on Aug 20, 2022 16:54:39 GMT -5
Thanks for the info
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