# Chengdeite - is it valuable?



## pursami (May 12, 2021)

I have researched for several days on chengdeite and while I have learned (and not much really) about this alloy, I have yet to discover what it the alloy is used for, etc. Is chengdeite valuable? If so, only for it's rarity alone or does it have an applicable purpose that is valued.




The pic is a 46 gram piece of chengdeite. Have total of 87 grams. XRF supports that it is chengdeite but no other testing has been done.

Any assistance to the question of value would be fantastic - is it a piece just for the mantle?

Thanks much.


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## Lino1406 (May 12, 2021)

Chengdeite is a mineral, not alloy but Intermetallic compound. It should be very precious. Please show XRF results


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## pursami (May 12, 2021)




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## g_axelsson (May 12, 2021)

I'm sorry to tell you that what you have is arsenopyrite, a quite good looking specimen. Too bad that you don't have a locality where it came from.

Arsenopyrite contains iron, arsenic and sulfur. An XRF that doesn't know about arsenic report it as iridium as the spectra is similar.

Another dead giveaway is either your hands are extremely tiny or the density of that piece is a lot less than if it was mostly iridium. The density of arsenopyrite is 6.07 g/cm3 and chengdeite is 19.19 g/cm3.

Arsenopyrite : https://www.mindat.org/min-305.html FeAsS
Chengdeite : https://www.mindat.org/min-1208.html Ir3Fe

Another dead giveaway is that chengdeite is a rare mineral that's been found as small grains about a mm in size or less at seven localities around the world while arsenopyrite is a common mineral that forms nice steel gray crystals and is found in more than 10.000 localities across the world.

Whatever you do, *don't try to dissolve it in acid or melt it*. There might have been a fatality among our members about two years ago and our long time member Irons had a near death experience that put him in a hospital bed for at least two months before he could go back home from smelting ore which contained arsenopyrite.

Göran


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## pursami (May 12, 2021)

Thanks - really appreciate the info! The find is from Peru. I am not seeing obvious similarities to arsenopyrite when looking at images (google). As you can tell, I am not a pro here. What type of lab would be recommended to do a serious test?


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## Lino1406 (May 12, 2021)

Break a small black cubic crystal, ask a chemist to put in nitric acid which is an arsenic dissolver. If most/all remains (my guess), that's not arsenic


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## pursami (May 13, 2021)

Thanks Lino - I will do as you suggest and take it from there. Will post any findings.


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