Silver?

[Chris Ben]

Went out detecting with my buddy Dave today, looking for a new spot. He killed it with 7 grams of gold. I did get a signal on a slope. 2 or 3 inches down to bedrock. The signal improved, but a I chipped away the bedrock it got stronger and stronger. Finally over a foot deep I break out a piece of quartz with copper mineral. It is screaming on my GPZ and on Dave's GB 2 also on a pin pointer. We go back to the truck I smash it open and find a silvery metal inside. It is also heavy for its size. About the size of a small plum. I didn't think Galena was very reactive on a detector?

Any ideas ?

Chris 

[Jim Hemmingway]

Hi Chris… that’s an attractive specimen you have there. It certainly looks like native silver. Have a look around the house for an unglazed white or beige porcelain type of surface. The unfinished bottoms of some types of soup bowls or coffee cups will suffice nicely for a simple streak test.

Silver is soft, it reacts to metal detectors similar to native gold, and it produces a silvery streak. Galena with sufficiently solid structure will certainly react to VLF metal detectors and pinpointers such as my Garrett Propointer. But none of my large galena samples will react to a PI unit. Galena produces a soft wide black streak that cannot be misidentified as silver.

The black mineralization adjacent to the silvery metal on your sample could also be comprised mostly of native silver with a black silver sulfide coating. That would help to explain the strong signal produced in the field. However,  it could very well be a silver sulfide such as acanthite or perhaps even a dark silver sulfosalt. I can’t be more specific from a photo, although I'd put my money down on it being native silver embedded in acanthite. In any practical sense, related silver minerals such as acanthite do not react to metal detectors in the field. 

 

[Chris Ben]

Hi Jim, thanks for your reply. Your specimens look great. I did a streak test, and it was black. Maybe it was the silver sulfide coating? My PI ,or the GPZ did pick it up from over a foot, so not sure. Also is there anything I should do the the specimen? To clean? Thank you

Chris

[Reno Chris]

Sometimes cuprite can appear very dark gray, almost black. Its real hard to do mineral ID by a simple photo - even a good clear one. Cuprite will make your detector sound off at a good distance.  Cuprite is a copper mineral that conducts electricity like a metal. Its often a very dark red but can range to a dark gray almost silver color.

[Chris Ben]

9 hours ago, Reno Chris said:

Sometimes cuprite can appear very dark gray, almost black. Its real hard to do mineral ID by a simple photo - even a good clear one. Cuprite will make your detector sound off at a good distance.  Cuprite is a copper mineral that conducts electricity like a metal. Its often a very dark red but can range to a dark gray almost silver color.

Thanks Chris, it definitely looks like a copper mineral. I'll keep trying to figure out what it is.

 

[Steve Herschbach]

Possibly chalcocite, another conductive copper mineral, and dark grey color more the norm.

[DolanDave]

Chris,

  Ill try to get an XRF on it sometime this week, hopefully tomorrow, and let you know.... very cool looking though.

Dave.

[Bob(AK)]

Chris, you now have several possibilities and I'll throw in another, covellite, closely related to 

Steve's  idea of chalcocite. What we collect is usually blue but I have seen some so dark it looks black.

[Jim Hemmingway]

Hi Chris… it’s a subjective decision, but for whatever it’s worth I wouldn’t do any treatment to your sample. It displays well and is otherwise quite an attractive specimen in its current state. Dave hopefully can satisfactorily identify it for you shortly. 

It is not a simple task to identify your mineral based on a photograph. A black streak test result implies a mineral compound, and not strictly a native metal. Some non-metal minerals do react to both VLF and PI units, producing good metalliferous type signals. In northeastern Ontario, these include solidly structured pyrrhotite, niccolite, cobalt, safflorite, skutterudite, and quite a number of potential silver-cobalt-nickel-iron-arsenide mineral permutations that you will never encounter in generally circulated mineralogical texts.

The silver mineral combinations are sufficiently complex and numerous as to require a reference list from the local museum, and more sophisticated identification techniques are required than the common mineral field tests normally available to hobbyists. We can easily imagine that such minerals would present insurmountable identification issues for hobbyists in the field and certainly the same applies in the context of forum discussion here.

Many of these minerals freshly exposed would produce a similar appearance to the silvery material in your photo. But the primarily cobalt-nickel-iron-arsenide related minerals do not necessarily account for the black host material in your photo with any real confidence. And frankly, I have no idea if these mineral types potentially even exist in your search areas.

There are other suggestions above, such as the enriched copper sulfides (bornite-covellite-chalcocite) that do produce VLF target signals, but do not react to my PI units. Unfortunately I’m not familiar with GPZ responses to various minerals because we have no hands-on experience with it to date.

Attached are a few mineral examples mentioned in this thread including a photo of low-grade cuprite (it’s all I’ve got). Chris R. above makes a perfectly viable case for this mineral’s consideration. Thanks for an interesting topic, it’s been an enjoyable diversion to post our possible solutions for you!!! 

[Chris Ben]

1 hour ago, Jim Hemmingway said:

Hi Chris… it’s a subjective decision, but for whatever it’s worth I wouldn’t do any treatment to your sample. It displays well and is otherwise quite an attractive specimen in its current state. Dave hopefully can satisfactorily identify it for you shortly. 

It is not a simple task to identify your mineral based on a photograph. A black streak test result implies a mineral compound, and not strictly a native metal. Some non-metal minerals do react to both VLF and PI units, producing good metalliferous type signals. In northeastern Ontario, these include solidly structured pyrrhotite, niccolite, cobalt, safflorite, skutterudite, and quite a number of potential silver-cobalt-nickel-iron-arsenide mineral permutations that you will never encounter in generally circulated mineralogical texts.

The silver mineral combinations are sufficiently complex and numerous as to require a reference list from the local museum, and more sophisticated identification techniques are required than the common mineral field tests normally available to hobbyists. We can easily imagine that such minerals would present insurmountable identification issues for hobbyists in the field and certainly the same applies in the context of forum discussion here.

Many of these minerals freshly exposed would produce a similar appearance to the silvery material in your photo. But the primarily cobalt-nickel-iron-arsenide related minerals do not necessarily account for the black host material in your photo with any real confidence. And frankly, I have no idea if these mineral types potentially even exist in your search areas.

There are other suggestions above, such as the enriched copper sulfides (bornite-covellite-chalcocite) that do produce VLF target signals, but do not react to my PI units. Unfortunately I’m not familiar with GPZ responses to various minerals because we have no hands-on experience with it to date.

Attached are a few mineral examples mentioned in this thread including a photo of low-grade cuprite (it’s all I’ve got). Chris R. above makes a perfectly viable case for this mineral’s consideration. Thanks for an interesting topic, it’s been an enjoyable diversion to post our possible solutions for you!!! 

 

On 1/8/2019 at 7:46 AM, Steve Herschbach said:

Possibly chalcocite, another conductive copper mineral, and dark grey color more the norm.

 

17 hours ago, Bob(AK) said:

Chris, you now have several possibilities and I'll throw in another, covellite, closely related to 

Steve's  idea of chalcocite. What we collect is usually blue but I have seen some so dark it looks black.

 

On 1/7/2019 at 9:45 PM, Reno Chris said:

Sometimes cuprite can appear very dark gray, almost black. Its real hard to do mineral ID by a simple photo - even a good clear one. Cuprite will make your detector sound off at a good distance.  Cuprite is a copper mineral that conducts electricity like a metal. Its often a very dark red but can range to a dark gray almost silver color.

These were the test results on the scan