The alloys on this variety have never really been studied. See Pollock for a listing of these. It is likely that other alloys exist. Pollock breaks these up as follows: Pure nickel J1771/P1986. It is not known if these are truly pure nickel. Nickel alloy including standard coin nickel and at least 6 varieties of German silver J1770/P1987. Copper alloy J1771A/P1988 At least 2 are known as noted below 1) Wilcox 2) Devonshire per Pollock, Heritage 8/96 ANA as J1770a, B/M 1/03 as J1770a, Stacks 1/08 as J1770a - PCGS64 74.5% copper, 12.9% iron, 2.6% nickel One of these was offered in Kosoff's 10/57 sale as lot 1091 and was forgotten or missed when the Judd book was being written. Aluminum J1772/P1989. Pollock lists 4 different alloys.