I don't have the Hard Rock book so not able to read that.

Twice as thick. Very interesting. Maybe, a original test piece ?

I have never heard of a .999 silver $1.00 Hard Rock. Certainly does not mean a test piece could not have been made.

Generally nickel $1.00 slot tokens weigh at or very close to .70 or an ounce were as .999 silver $1.00 tokens weigh between .80 and an ounce, all weighed at troy.

X-rayed only. No acid test as that scratches even if on the outer rim.

Please do post and let us all know what the test results are.

Thanks a bunch, Dennis