- Composition: The 40 percent silver Ike dollars are composed of 40% silver, 53.5% copper, and 6.5% manganese. This differs from the standard composition of 90% silver and 10% copper used in previous Eisenhower dollars.
- Weight: The 40 percent silver Ike dollars weigh approximately 24.59 grams, while the standard silver Ike dollars weigh about 22.68 grams. This weight difference is due to the higher density of silver compared to copper.
- Color: The 40 percent silver Ike dollars have a darker, almost grayish color compared to the brighter, whiter color of the standard silver Ike dollars. This difference in color is due to the higher copper content in the 40 percent silver alloy.
- Mint Mark: All 40 percent silver Ike dollars were minted at the San Francisco mint. Look for the "S" mint mark on the reverse side of the coin, below the year of issue.
Please note that the 40 percent silver Ike dollars were only produced in 1971, 1972, 1973, and 1974. The 1975 Ike dollars were composed of the standard 90% silver and 10% copper alloy.