(1964-65) Blank Pattern - RB-6040, INCO

Coin Details

Description

INCO experimental blank planchet RB-6040, the fifth entry in the regular RB-60xx subseries. This composition marks the midpoint of the early RB-6xxx group (RB-6000 through RB-6060), indicating a composition that represented a median or reference point within this alloy family. The blank planchet's role in the experimental hierarchy was unique: while struck patterns could be evaluated for their visual appeal, design fidelity, and public acceptability, only blanks could provide unambiguous data about the alloy's raw material properties. This distinction was critical for the Treasury's metallurgists, who needed to separate the effects of alloy composition from the effects of die design and striking parameters when evaluating each candidate material. A blank that performed well on raw property measurements could be advanced to the struck-pattern stage with confidence, while a blank with marginal properties could be eliminated without expending the resources required for die preparation and trial striking. RB-6040 documents one composition that passed this initial screening threshold.

Rarity Notes

R-7 to R-8. Very limited production for technical evaluation purposes.

Cross References

RB-6040 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-6xxx group, 1964-65.