(1964-65) Blank Pattern - RB-5220, INCO

Coin Details

Description

Experimental quarter-sized blank planchet RB-5220 from INCO's silver replacement program. This composition variant completes the initial group of RB-52xx blanks, representing one of the alloy formulations evaluated for the quarter denomination before the series transitions to the RB-5300 numbering block. The gap between RB-5220 and the next known entry at RB-5300 may indicate a categorical distinction in the experimental program — a shift from one family of alloys to another, such as moving from copper-nickel formulations to compositions incorporating additional elements or different layer architectures. Blank planchets provide information that cannot be obtained from struck coins: the true surface finish of the raw alloy without die-imparted texture, the precise thickness and uniformity of the planchet before striking compression, and the mechanical properties of the metal in its pre-struck state. For a denomination as commercially important as the quarter, every aspect of the planchet's quality had to meet exacting standards before any composition could advance to the struck-pattern stage of evaluation.

Rarity Notes

R-7 to R-8. Rare survivors from a scientific evaluation program that consumed many of its own specimens through destructive testing.

Cross References

RB-5220 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.