John Paul II 1980 Cologne visit [solved]

Hi. I wonder if anyone can give me a bit more information on this medal please. What I know so far is that it was issued in a first day cover to commemorate the Pope's visit to Cologne on 1980. Its dimensions are around 32.7mm diameter, 2.2mm thickness and weighs 15.1g. Basically the main info I'm after is what metal it was minted in, the patina to the coin and general colour suggests silver to me (grade unknown), but I don't know if that works for its diameter and weight. Any extra information much appreciated, thanks.

Sorry, I've found out my answer myself once I got the Microscope out; the tiny writing on the reverse says ARGOR 999.9, so effectively pure silver.