(1964-65) Blank Pattern - RB-6060, INCO

Coin Details

Description

INCO experimental blank planchet RB-6060, completing the initial seven-entry RB-60xx subseries that began with RB-6000. As the terminal entry in this first group, RB-6060 represents the last composition explored at regular ten-unit intervals before the numbering shifts to the RB-61xx subseries, which begins at RB-6100. The gap between RB-6060 and RB-6100 is significant — a forty-unit jump that indicates a categorical boundary between two distinct alloy families or experimental approaches within the broader RB-6xxx program. RB-6060 thus occupies a boundary position, documenting the final composition in one line of investigation before the program pivoted to a new direction. These boundary compositions are particularly valuable for understanding the experimental program's internal logic, as they reveal where INCO's researchers decided that one approach had been sufficiently explored and a fundamentally different strategy was warranted. The blank's physical properties — measured and documented alongside all other entries in the series — would have been compared against the RB-6100-series results to evaluate the relative merits of each approach.

Rarity Notes

R-7 to R-8. Rare terminal entry in the RB-60xx subseries, potentially surviving in smaller numbers than earlier entries.

Cross References

RB-6060 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-6xxx group, 1964-65. Final entry in the RB-60xx subseries.