(1964-65) Blank Pattern - RB-5370, INCO

Coin Details

Description

INCO experimental quarter-sized blank planchet RB-5370, approaching the end of the RB-53xx series. This composition represents one of the final variants tested in what was the most thoroughly investigated alloy family in the quarter-denomination blank program. The persistence of closely spaced entries through RB-5370 and beyond indicates that INCO continued to explore compositional refinements even as the broader program was converging on a recommended alloy. This thoroughness reflected both scientific discipline and commercial strategy — by testing every plausible variation within the promising composition space, INCO could present the Treasury with a comprehensive understanding of the alloy system's capabilities, strengthening the case for their recommended formulation. The blank's physical characteristics — its weight, color, surface finish, and edge appearance — would have been indistinguishable to an untrained eye from many of its neighbors in the series, but the subtle differences in metallurgical composition were precisely what determined each alloy's suitability for mass production.

Rarity Notes

R-7 to R-8. Extremely limited production, with surviving specimens primarily in advanced pattern collections.

Cross References

RB-5370 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.