This medal commemorates the restoration of St. Giles Church in Edinburough in 1883. Brown's British Historical medals (#3157) lists versions in gold, silver and white metal while the NY Historical Society describes their piece as aluminum (http://www.nyhistory.org/node/57007. The piece shown below does not have the high-point darkening which is common to white metal medals and is more of a uniform light grey. Is there an easy way to tell what it's actually make of? Thanks!
The weight should be substantially different between white metal and aluminum. So much so that I'd think you could tell the difference just by holding it (as I know you have quite a collection of medals). Alternatively, with approximate diameter measurement and thickness measurements you could calculate approximate volume (and subsequently mass). Aluminum weighs 2.7 grams per cubic centimeter. White metal (which I usually think of as being close to lead or tin) weighs around 7.4 grams per cubic centimeter (tin) or around 11.3 g/cm3 (lead). Edit: did a little math. If your medal is 45mm diameter, and assuming it's about 3-4mm thick then it's volume is roughly 4.8-6.4 cm3. If it is made of aluminum it should have a weight of 13 to 17 grams. If it is made of white medal (usually made of some combination of copper, tin, lead, antimony...etc -- all much heavier than aluminum) then it would weigh 44 to 70 grams. Now, if you mean a chemical test for determining its metallurgic composition, I know that NGC has capability to perform such a test -- but I'd say that's beyond the everyday capabilities of most people machinery wise.
I can remember seeing bronze cathedral medals at 1 coin show in Las Vegas. they were belgian medals. the depth perception on those medals were so incredible. I wanted 1 but could not afford it. lol $300-1,000.
The medal is 4mm thick at the rims but the rims are high and the obverse and reverse faces are closer to 3mm apart. The weight is approximately 27 gms which apparently doesn't help! Ed. Well at least that rules out aluminum. (My understanding is that the process used to produce aluminum efficiently wasn't even available in 1883.)
Well drat! With that weight, it's density is somewhere around 4.9 to 5.7 grams per cubic centimeter. I can't find any feasible metals (or alloys) that have that density profile. :scratch:
In the late 1800's aluminum was almost a precious metal, because it's so hard to work with. I have seen jewelry, not considered costume, made out of aluminum, before 1900. Your coin is white metal, which describes a handful of different alloys.
