(1964-65) Blank Pattern - RB-5375, INCO

Coin Details

Description

Quarter-sized experimental blank RB-5375, one of the final entries in the main body of the RB-53xx INCO composition series. This planchet records a composition variant that was among the last to be tested before the series transitions to the more widely spaced RB-5400 numbering block. The density of entries in the RB-5300-5375 range — with compositions at nearly every five-unit interval — stands in contrast to the sparser distribution of entries in the subsequent RB-5400-5420 range, suggesting a transition from intensive optimization to broader exploratory testing of alternative approaches. This blank, like all others in the series, was produced at INCO facilities and delivered to the Treasury for evaluation alongside detailed technical specifications. The evaluators could hold the blank, weigh it, examine its edge, test its electromagnetic properties, and compare it against a standard silver quarter blank — a hands-on comparison that complemented the numerical data provided in INCO's technical reports.

Rarity Notes

R-7 to R-8. Rare experimental planchet from the final intensive phase of the RB-53xx composition study.

Cross References

RB-5375 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.