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Found a 70 Pound Slab of Metal; Is There a Home Test for Rhodium?a September 5, 2008
I've found this 70+ lb silver slab of something. I was panning for gold when I came across it. It's 70+ lb and it's only 6 in x 8 in maybe 2 inches thick in some places, so it's got my curiosity flying all over the place. When I first brought it home I dusted it off and put the whole thing in Muriatic Acid [linked by editor to product info at Amazon] for a good 6 hours and in all due respect, this piece is not breaking down whatsoever.
After inspecting it I noticed right away a silvery shine to it. I filed some of the metal off of it and put it into muriatic acid--not much of a reaction and the mixture turned bright green. It's got me stumped but I'm sure it's something valuable because it won't break down (tough stuff). Is there a test I could perform at home to test for Rhodium? (Just hoping.)Jostlyn McCarter
hobbyist - Salt Lake City, Utah
September 18, 2008
Hi, Jostlyn. It's unlikely that someone misplaced a ten million dollar slab of rhodium :-)
Rhodium is so rare and dispersed that even at its astronomical price it has never been refined except as a byproduct of platinum, and a rhodium mine has never been discovered on this planet. It's not rhodium.
You can see how much it weighs and how much water it displaces and thus determine its density (Archimedes Principle). That won't tell you exactly what it is, but will tell some things that it's not; the heavier it is, the more things it isn't. You can see if your library can get you a copy of "Rapid Spot Testing of Metals & Alloys" [link is to info about the book at Amazon]by A. Holmes. Can you find a jeweler who is equipped to quickly tell you what this slab is? Good luck.
Ted Mooney, P.E. RET
Pine Beach, New Jersey