https://www.bavarikon.de/object/bav:ASM-OBJ-0000000000000017?lang=de states that one of the five small coins - the one "of Bohemian type" is almost pure gold, while the other four (local Manching type) are alloyed with 20 percent silver and copper. No mention is made of the composition of the largest (and apparently unembossed) coin