(1964-65) Blank Pattern - RB-6125, INCO

Coin Details

Description

INCO experimental blank RB-6125, another closely spaced entry in the intensive RB-61xx composition study. The cluster of five-unit-interval blanks in this range (RB-6115, RB-6120, RB-6125, RB-6130) represents the densest concentration of experimental compositions in the entire RB-6xxx series, indicating that INCO's metallurgists had identified this region of the alloy space as particularly promising. Each five-unit increment corresponds to a small but deliberate change in one or more alloying elements — a half-percent increase in nickel content, a slight adjustment to the copper-to-other-metal ratio in the core, or a minor modification to the cladding layer thickness. These subtle changes could produce measurable differences in the planchet's electromagnetic response, surface appearance, or mechanical properties, and the goal of testing each variation was to map these relationships with enough precision to specify a production alloy that would meet all requirements simultaneously. RB-6125 is one data point in this precision mapping exercise.

Rarity Notes

R-7 to R-8. Extremely rare. The dense clustering of compositions in this range makes each individual blank a significant record of the optimization process.

Cross References

RB-6125 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-61xx group, 1964-65.