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 J1767A/P1981. It is not known if these are truly pure nickel. They are magnetic. At least half a dozen are known.
Nickel alloy including standard coin nickel and at least 6 varieties of German silver J1767/P1982. This is common.
Bronze alloy J1768/P1983 & P1985A Two different die pairings are known for these differing in the alignment of the head of the eagle on the pole with relation to the 'S' in 'Pluribus' on the obverse and the position of the letter 'T' in 'Cent' with relation to the numeral '1' on the reverse. Pollock lists at least 4 different alloys. The illustrated P1985A is the rarer of the 2 varieties with about a half dozen known.
To see both obverse dies side by side, click here.
To see both reverse dies side by side, click here.
Brass J1768A/P1984 This is not listed in Judd but an example was slabbed as a J1768A. Pollock lists two different alloys with others likely and was probably the first of the 2 dies.
Aluminum J1769/P1985. Pollock lists 4 different alloys. There are at least a dozen known.