(1964-65) Blank Pattern - RB-5360, INCO

Coin Details

Description

INCO experimental quarter-sized blank planchet RB-5360, part of the later entries in the RB-53xx composition series. The numbering gap from RB-5350 to RB-5360 (skipping RB-5355) may indicate that the intervening composition was either not produced in blank form or did not survive. As the RB-53xx series moves into its higher numbers, the blanks may represent compositions that explored the outer boundaries of the promising alloy space identified through the earlier intensive testing in the RB-5320-5350 range. Boundary compositions are valuable in experimental metallurgy because they establish the limits beyond which a given alloy property degrades unacceptably, thereby defining the range of acceptable production specifications. For a coinage alloy intended for production in billions of units, manufacturing tolerances needed to be wide enough to accommodate normal industrial variation while remaining narrow enough to ensure consistent coin quality. RB-5360 may represent a composition near the edge of this acceptable range, helping INCO define the manufacturing specifications that would accompany their recommended alloy.

Rarity Notes

R-7 to R-8. Extremely rare. Higher-numbered blanks in the series may survive in especially small quantities.

Cross References

RB-5360 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.