(1965) Quarter Pattern - RB-4120, INCO

Coin Details

Description

Experimental clad quarter RB-4120, a mid-series entry in INCO's 1965 quarter composition testing program. This piece represents one of the alloy variants produced as the experimental program moved from exploratory testing toward production validation. The copper-nickel clad composition ultimately adopted for quarters consisted of a pure copper core bonded between two outer layers of 75% copper and 25% nickel, creating a three-layer sandwich with an overall composition of approximately 91.67% copper and 8.33% nickel. RB-4120 may test a formulation close to but not identical to this final specification, as INCO's engineers explored alloys both above and below the target nickel content to map the performance envelope of the clad concept. Struck at the Medallic Art Company on Washington quarter dies, this piece exhibits the full design detail of a production quarter while containing an alloy that may differ subtly in color, weight, or electromagnetic properties from the composition eventually adopted. These differences, while often imperceptible to the naked eye, were critically important to the vending machine industry, whose equipment needed to reliably accept the new clad coins while continuing to reject counterfeits.

Rarity Notes

R-7 to R-8. Extremely rare, with an estimated fewer than 10 specimens documented. Mid-series RB numbers in the quarter program tend to survive in slightly greater numbers than the earliest and latest entries.

Cross References

Research Blank RB-4120 (Gould/INCO experimental series)