Can Anyone Help Me Find Out Any Information About A 1974 Lincoln Memorial Cent Tnat Was Struck In Brass And Not Copper???
Color is a very unreliable diagnostic. Given the right chemical environment, you can turn a cent almost any color imaginable. If weight and specific gravity are the same as a normal cent, then it's probably just an odd color. The quickest method is to scrape the edge against a fine sharpening stone (yeah, I know it's frowned upon, but I like my answers fast and incontrovertible). If the color is the same as normal, freshly exposed copper, then you know you're dealing with surface discoloration. If it remains brassy, then you've got case. But weigh the thing before you do anything else.
The US mint makes coins for many other countries; it's not unheard of for a foreign planchet there to find its way into a press making American coins. It would be odd if it were exactly the same size as a cent (but not impossible). Is it a different size? Do weigh and measure it. I wouldn't nick it as advised above.
Invasive tests are not for everyone. But I've found them useful over the years to detect anomalous compositions and reject claims of nonstandard compositions. It's quicker, and a lot cheaper, than an SEM/X-ray test. But I always weigh the coin first, measure its diameter, test its ring, and perform a specific gravity test. That usually obviates the need for an invasive test. Years ago I bought a BU cent allegedly struck on a brass planchet. It sure looked like brass. The weight and diameter were normal. I scraped the edge against a fine sharpening stone and revealed a normal copper color dramatically different from the surface color. I sent the coin back and got my money back.
The problem with determning brass/copper/bronze composition is that weight and specific gravity tests usually are indeterminate unless it is something like a 60- 70 % copper 30 - 40% zinc alloy. Brass can be any combination of copper and zinc but once the zinc drops to the 5 - 10% level it can have the same color as copper or bronze and can also tone or tarnish to roughly the same color as well. (And most references on foreign coins don't bother to give the compostion percentages, they just say brass.) And copper, brass, and bronze have almost identical specific gravities. The only REAL way to tell the composition is through the SEM/w-Ray test, or through destructive assay. I run into this problem a lot with Chinese coins. Many issues come in common varieties made of copper, and rare varieties made of "brass", but with no percantage compositions given. A cleaned copper coin LOOKS like brass, but so does a cleaned brass coin. And without a listed percentage composition, for all I know the description of the brass variety may have been taken from a cleaned copper coin. For that reason I have simply decided that most if not all of the brass varieties probably don't exist because that can not be definitively identified.
I Sent This One To Anacs For Verification And Grading. When I Get The Results Back In About A Month, I Will Let Everyone Know What The Real Answer Is. In The Meantime You Can Just Keep Guessing.
