Copper Vs. Nickel Vs. Silver

This sort of question unfortunately, can only yield nebulous answers.

The reason for this is that no modern coins currently made for circulation are made out of copper silver or nickel as pure metals.

For coins minted in the past, the reason submitted above is not correct. For some coins during the first part of the 19th century, pure copper was indeed used. For example, British farthings, Halfpennys Pennys and Twopences. Pure copper coinage was later replaced with bronze coinage. One of the reasons for this is that bronze has better wearing qualities in circulation.

These days, we all aware of Zincolns and clad coinage. A lot of circulation coinage around the World has three or more metals in their makeup. One of the main reasons for this (among others) is that they have better wearing qualities in circulation.

If my memory serves me correctly, the Brinnell Hardness Test is used for pure metals and alloys. It uses the technique of a diamond cone pressure test, with a standard test load, where the depth of the cone indentation is measured.

The scratch test (Moh's Hardness) is more used for minerals and gemstones, and is not relevant to hardness testing for coinage metals. I have been a gemstone facetor for about 20 years.

Pure nickel, used by Canada, France, Switzerland and numerous other countries in the past, is much harder-wearing than either gold or silver. Given several years of heavy circulation, a nickel coin will still look near-pristine and lustrous while a silver coin will be noticeably worn and dull. It's also much harder to actually strike the coins, making weak strikes and generally "flat" designs common in these series.

Pure copper is only slightly better-wearing than pure silver in coins, but neither are typically used for circulation coinage. Bronze (circulation "copper") is harder-wearing than sterling (.925 fine) or metric (.900 fine) circulation silvers.

The problem with any possible answer is just who handles the coins and how. For example my neighbor's hands are really tough so the coins he handles end up worn faster than my coins. So regardless of teh metal, you need to know who is using the coins. And too the kids in our Chem labs find ways to melt almost any metal so hardness is irrelevant.