1964 Quarter Pattern - RB-2535, INCO

Coin Details

Description

Experimental quarter struck in the RB-2535 alloy composition during INCO's landmark 1964 clad coinage development program. This piece occupies a position in the middle-to-upper portion of the RB-25xx sub-series, representing a composition that had been refined through multiple rounds of iterative testing. The Reed-Brenner classification system preserves the sequential logic of INCO's experimental approach: compositions were tested, results were analyzed, and the next round of compositions was designed to explore the most promising directions indicated by the data. By the time the RB-25xx sub-series was being produced, the general characteristics of the winning composition were becoming clear — a copper core with copper-nickel cladding in proportions that balanced cost, appearance, and electromagnetic compatibility. The specific formulation that was ultimately adopted (75% copper, 25% nickel cladding over pure copper core) first appeared as a numbered composition somewhere in the RB-25xx range, though establishing exactly which RB number corresponds to the adopted composition requires metallurgical analysis that has not been comprehensively performed on all surviving specimens. RB-2535 may thus represent a composition very close to or even identical with the alloy that now constitutes every American dime and quarter.

Rarity Notes

Extremely rare. Population estimated at 1-5 specimens. The potential proximity of some RB-25xx compositions to the adopted formulation adds numismatic interest.

Cross References

RB-2535 (Reed-Brenner), NGC ID: 61895