I have always believed that the $10 silver strikes contain .6 ounce of .999 silver. Slightly over 1/2 ounce of silver.
It depends. The $10 Silver Strikes made before 2006 contain six-tenths of an ounce of silver; Silver Strikes made 2006 and later contain one-half ounce of silver.
Anyone wanting more information about these casino tokens can go to the Silver Strikers Club link below. Silver Strikers Club - Home Page
What I've always wondered (made me scratch my head) was the people who separated the brass ring from the silver to recycle the metal. There are many collectors who would pay more for the complete strike.