(1964-65) Blank Pattern - RB-5340, INCO

Coin Details

Description

Experimental quarter-sized blank planchet RB-5340, continuing the intensive composition optimization within the RB-53xx alloy family. This blank represents another incremental step in INCO's parametric study, testing a formulation that differs slightly from its RB-5335 and RB-5345 neighbors. The subtlety of these compositional differences is itself informative — it indicates that INCO had moved beyond the broad-stroke exploration of fundamentally different alloy systems and was engaged in the precision fine-tuning that characterizes the final stages of alloy development. At this level of refinement, changes of a fraction of a percent in a single alloying element could shift the electromagnetic response enough to move it closer to or further from the target value established by 90% silver. The blank planchet's edge is particularly diagnostic at this stage, as the cross-sectional appearance of the clad layers varies with composition in ways that directly affect the visual character of the finished coin. A composition that produced a barely visible edge stripe might be preferred for aesthetic reasons, while a composition whose edge revealed a stark contrast between cladding and core would draw attention to the coin's non-silver nature.

Rarity Notes

R-7 to R-8. Extremely rare experimental blank from the precision optimization phase of INCO's alloy development program.

Cross References

RB-5340 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.