Native silver

A question - is it assumed that all native silver specimens should be tarnished black? Sometimes the silvers are rather silvery to very slightly discolored. Were these specimens treated in some way to discourage tarnishing and, if so, does this treatment put the specimen into the realm of fakery?

Probably most of them were treated chemically to brighten the silver. There are several ways to do this chemically. The easiest is to used a commercially prepared solution called Tarnex which is a slightly acidified water solution of thiourea.

Rock Currier
Crystals not pistols.

Actually Barry has fingered a problem with Silvers. Untreated silvers blacken at different rates, some seem never to blacken while others go quickly. I don't know the reason.

I had a "fatal" test when placed one of my silver with opened with pyrites, marcasites and other sulfides... Some more specimens were staying in plastic boxes with edges hermetically glued with scotch with quartz specimens. Within a few months the first silver become totally black while others remain as white "as new". So I guess the sulfur is one of the common reasuns for silver blackening - so we have silver covered with acanthites. I have no idea about the reaction of silver with oxygen, but since it's an active element, i'd better put it away from any contact with open air.
As for considering the cleaned silver a fake, I don't think it can be called a fake.... we have tons of uvarovite specimens coming from Urals totally etched from calcite... and still no one is calling them a fake - and that's a kind of a cleaning method.
Another question is when a silver wire is glued to some matrix, which is regretfully also takes place - this produces a fake for sure.
By the way, great amount of US copper is cleaned to the brass bright condition - also a fake?

A tip is to be very very careful with cleaning any native silver specimens.
My experience is not only my own, but also from many Kongsberg collector friends and the Norwegian Mining Museum in Kongsberg.

If cleaned with any more reactive agent, this seem to very much speed up the oxidation! If cleaning any specimens use very slight acidic solution
such as water with slight citric acid. Be sure to have clean (BUT NOT DESTILLED WHATEVER YOU DO!) water!

If cleaned strongly it could blacken heaily in a couple of weeks, insteda of hundreds of years!

I believe that it is the sulfur that is the main problem here. I know that some museums are now treating the air the flows through display cases containing silver items with air purifiers to remove atmospheric sulfur. Usually the sulfur comes from human gas emissions; in the case of pyrite / marcasite / arsenopyrite in close proximity, these too can be a source of sulfur. Don't eat beans and then hold your native silver
Perhaps some chemists can chime in on this as well?

You are right, Jeffrey..."human gas emissions" in fact contain sulfur...although not in the amounts high enough to tarnish silver specimens, leave alone silverware...
(Sorry, couldn't resist.)

No yoke..in silver jewelry the yolk of an egg can be used to oxidize accent areas and backrounds...so for sure any sulfide is going to tarnish the silver

Michael H. - Perhaps you are right, but I was recently working on a proposal for a air purification project, specifically aimed at removing sulfur, and several of the references sources cited this museum issue. Of course, there could be mutiple sources of air-bourne sulfur containing chemicals (mostly H2S and COS) aside from people. Air purification is an interesting application for zeolites, by the way.

Over the decades as a silversmith I picked up little trick that help SLOW DOWN the tarnish on silver. This doesn't stop it but it slows it down and it is completely safe for specimens.

Chalk, as in blackboard chalk from a school, naturally absorbs sulfur compounds from the air. I don't know the chemistry behind this but I know hundreds of silversmiths and jewelers that use it. I put it in all our display cabinets at our store and any specimen drawers or boxes that have silver or copper specimens in them. In a box or drawer it will slow it down to the point a silver or copper will last years before it starts to show any oxidition.

I was shown this little trick by a doctor who was also a silversmith.

Much of the commercial silver jewelry is sprayed with a thin coating of lacquer to keep it from oxidizing. Using chalk is much more friendly to a specimen.

Thanks,
Rick Dalrymple