(1964-65) Blank Pattern - RB-6140, INCO

Coin Details

Description

The final documented entry in the entire INCO experimental blank planchet program, RB-6140 closes out both the RB-61xx subseries and the broader RB-6xxx series. As the terminal catalog number across all of INCO's unstruck blank test pieces, this planchet represents the conclusion of an extraordinary experimental effort that produced at least sixty-two distinct blank compositions across the RB-5xxx and RB-6xxx numbering ranges. The completion of the blank program coincided with the political resolution of the silver crisis: on June 3, 1965, President Lyndon Johnson submitted the Coinage Act of 1965 to Congress, and on July 23, 1965, he signed the legislation that authorized the transition from silver to copper-nickel clad coinage. The alloy ultimately selected for production — 75% copper / 25% nickel cladding over a pure copper core — drew on the extensive body of experimental data generated by programs like INCO's, though the final production specification also reflected input from the Treasury's own testing, from competing suppliers like Gould, and from the vending machine industry's electromagnetic acceptance requirements. RB-6140 stands as the capstone of INCO's blank planchet contribution to one of the most consequential changes in American monetary history.

Rarity Notes

R-7 to R-8. As the final entry in the entire INCO blank planchet series, this piece holds special significance for catalogers and historians of the silver-to-clad transition.

Cross References

RB-6140 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-61xx group, 1964-65. Final entry in the entire INCO RB-series blank planchet program.