(1964-65) Blank Pattern - RB-6115, INCO

Coin Details

Description

INCO experimental blank planchet RB-6115, situated between RB-6110 and RB-6120 in the RB-61xx subseries. The five-unit interval from RB-6110 to RB-6115 mirrors the fine spacing observed in the most intensively studied portions of the RB-5xxx series, indicating that this region of the RB-6xxx composition space received particularly detailed attention. Such close spacing typically indicates that the researchers had identified a promising composition and were conducting precision optimization, testing small incremental changes to find the exact formulation that maximized performance across all evaluation criteria. The blank's position within this closely spaced cluster indicates that RB-6115 explores a composition very near the optimum for whatever alloy family the RB-61xx series represents. The existence of a five-unit entry (6115) alongside the ten-unit entries (6110, 6120) is itself diagnostic, indicating that INCO's researchers deemed this region important enough to warrant additional data points beyond the standard ten-unit experimental grid.

Rarity Notes

R-7 to R-8. Extremely rare fine-increment composition variant, indicating intensive optimization testing.

Cross References

RB-6115 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-61xx group, 1964-65.