They are 56% copper, 35% silver, and 9% manganese. Most other silver coinage in the US is 90% silver.
How do I know, CCF tells me.
Check out the left hand column.
Go to the section '
US coins & Currency'.
Click on 'US Coin Facts'.
There you will find basic information on all
US coinage.
Tons of great info in that left hand column.