Got A Tricky One - Industrial Silver Ingots

Very interesting.

Yes, an XRF machine is expensive to obtain but is more accurate than an acid test. I've never used an acid test, but it's my observation from responses reported on the forum that they're not as reliable (or at least are more prone to user error) than the equivalent gold acid tests.

XRF also has the benefit of being non-destructive. An acid test, by definition, must scrape off a small piece of the object in question and then test that piece with the acid. You obviously don't want to do this to a possibly-collectable coin if alternatives are available. This obviously isn't an important consideration for these specific objects.

None nearby no.

I went to the biggest jeweler in town yesterday - not very helpful. They didn't even have a way to test purity.

Going to take them to a scrap metal place probably Friday, and then a good coin shop later perhaps Saturday, that said they could test them.

Bummer. Thank you for the update.

OK - though looking at the site I'm not sure they do this kind of thing. You have to request a quote online - there's no way they'd do that without assay, so I'd need to send them in before getting a quote.

"Silver solder" would be closer to 70% silver composition - that's the eutectic point of a silver-copper mixture, the alloy with the lowest melting point. The quoted alloy has about the same melting point as pure silver; thus impractical for that purpose. 30%-35% silver alloys can work in things like brazing, but they need something more like a 33:33:33 mixture with a third element (usually either zinc or cadmium, or both) to be useful.

Nor is it likely to have been an electrical application, since people like using silver in electronics for it's high conductivity, but the conductivity of this alloy is much worse than for normal high-purity silver - you might as well use pure copper or some other less-conductive metal that's not as pricey as silver.

It's original purpose might remain a mystery, and might depend on what that "missing 5%" in the chemical analysis turned out to be. I'd frankly expect a piece of 35% silver - 65% copper alloy to look more... pinkish or coppery than what we see in these pictures; I suspect that mystery element might be helping make it look more silvery.

Not sure. Didn't bother weighing individual ones or counting them.

There were about 3-4 one-off pieces of different sizes, but otherwise they all looked the same. Didn't look like precision cuts though, like a coin or the like, as if they are blanks.