(1964-65) Blank Pattern - RB-6130, INCO

Coin Details

Description

Experimental blank planchet RB-6130, marking the end of the densely clustered optimization region within the RB-61xx subseries. The transition from RB-6130 to the next known entry at RB-6140 — a ten-unit gap rather than the five-unit intervals seen from RB-6110 through RB-6130 — indicates that the intensive parametric study concluded at this composition and the program returned to broader exploratory spacing. This pattern is characteristic of well-designed experimental programs: intensive investigation of the most promising region exhausts the useful information available from small compositional increments, and the researchers move on to test more widely separated formulations that might reveal new alloy families of interest. RB-6130 thus occupies a pivotal position in the experimental narrative — it represents the final fine-tuned variant in what was apparently the most promising composition space within the RB-6xxx program. The blank preserves in physical form the composition that INCO's metallurgists identified as the practical limit of useful optimization within this particular alloy system.

Rarity Notes

R-7 to R-8. Rare terminal entry in the densely studied RB-6110-6130 optimization cluster.

Cross References

RB-6130 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-61xx group, 1964-65.