The information below is primarily excerpted from Pollock and from the August 30, 1993 and September 6, 1993 issues of Coin World by Kenn Henderson.
This metallurgical trial was produced by the International Nickel Company in 1964. They were one of several companies the U.S. Mint commissioned to find a suitable alloy replacement for silver.
The obverse features a bust of Dr. Paul D. Merica and the reverse features his laboratory where the pieces were struck. The design was created by Gilroy Roberts and the hubs were created by the Medallic Art Company.
These were issued in sets with a dime sized coin P5335 and a quarter sized coin P5340.
Examples were struck as follows:
P5375 95% nickel, 5% silicon on a permalloy core of 79% nickel, 16% iron and 5% molybdenum with a plain edge.
P5376 95% nickel, 5% silicon on a permalloy core of 79% nickel, 16% iron and 5% molybdenum with a reeded edge.
Photo courtesy of American Numismatic Rarities.