(1964-65) Blank Pattern - RB-5210, INCO

Coin Details

Description

Experimental quarter-sized blank planchet RB-5210, produced by INCO as part of the comprehensive alloy testing program for the United States Treasury. This planchet documents a third composition variant within the RB-5200 sequence, offering Treasury metallurgists another data point in the systematic comparison of candidate alloys. The manufacturing process for these experimental blanks closely paralleled the production method that would eventually be used for billions of circulation coins: ingots of the experimental alloy were rolled to the precise thickness required, then individual blanks were punched from the strip, annealed, and tumbled to produce the smooth, uniform planchets required for high-speed coining operations. By examining blanks at each stage of this process, INCO and Treasury engineers could identify potential manufacturing difficulties before committing to full-scale production trials. The edge of each blank reveals the internal structure of the clad sandwich — the contrasting colors of the cladding and core layers visible as a distinctive stripe that would become the most recognizable feature of post-1964 American coinage.

Rarity Notes

R-7 to R-8. These blanks were produced strictly for metallurgical evaluation and survive in very small numbers.

Cross References

RB-5210 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.