(1964-65) Blank Pattern - RB-5205, INCO

Coin Details

Description

Quarter-sized experimental blank planchet RB-5205 from the INCO silver replacement program. This unstruck planchet represents a distinct alloy composition from RB-5200, with modifications to the metallic formulation that would produce different properties in the finished blank. The study of blank planchets was an essential component of the Treasury's evaluation methodology. Metallurgists could cross-section these blanks to examine the bonding interface between the outer cladding layers and the inner core under magnification, checking for delamination, porosity, or incomplete fusion that might cause the layers to separate during striking or circulation. Each composition in the RB-5xxx series underwent this kind of destructive testing alongside non-destructive evaluation of surface properties and electromagnetic characteristics. The quarter-sized format of the RB-5xxx blanks corresponds to the denomination that generated the most intense scrutiny during the transition study — the quarter's ubiquity in vending machines and its prominent role in everyday transactions made it the coin whose replacement alloy demanded the most rigorous validation.

Rarity Notes

R-7 to R-8. Surviving blanks from the INCO program are institutional rarities, many having been consumed in destructive metallurgical testing.

Cross References

RB-5205 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.