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Identity HelpFungus on chalcopyrite?

19th Nov 2018 19:48 UTCBrent Thorne Expert

Attached is a photo of something growing on chalcopyrite. FOV 1mm. It looks to me like fungus? The specimen has hessite, and gold on it and it is from the Trixie mine, Utah Co., Utah.

Any ideas would be appreciated.

Brent Thorne

19th Nov 2018 21:27 UTCReiner Mielke Expert

Can't tell what it is from that photo.

19th Nov 2018 21:34 UTCAlfredo Petrov Manager

Isn't copper toxic to fungi? Why would a fungus preferentially grow on chalcopyrite and not on the less toxic neighboring matrix? I guess it's either a secondary copper mineral and you'll need an electron microscope shot to see the crystal shape, or else it's an alien life form. Interesting, whichever it is. ;))

19th Nov 2018 22:35 UTCThomas Lühr Expert

It is even known a mold fungus that grows on used (=silver bearing) photographic fxing bath. But don't ask me for the species name ;)

19th Nov 2018 23:46 UTCBrent Thorne Expert

I realize the photo is not very sharp, but the chalcopyrite is in a vug of quartz and the unknown growing on the crystal is extremely small. The photo was take at a FOV of 1mm. That means the chalcopyrite crystal is about 500 microns. I am not sure that any more magnification would get a sharper picture.

Thank -you for the comments. I had not heard of a fungus that grows in silver bearing fixing baths. There is a lot of hessite in the associated quartz. I will look into it.

I have seen covellite growing on and around some metallic copper species. I just have never seen anything like this.

20th Nov 2018 11:04 UTCUwe Kolitsch Manager

You could treat it with acetone and see what happens.

My guess is a copper (or silver) sulphide.

20th Nov 2018 13:44 UTCChristian Auer 🌟 Expert

I agree with Uwe especially when its an older (= not fresh collected) specimen.