My small collection of silver coins

The one in the bottom is a 1928 soviet 10 kopeck silver coin
I like the word written in the back "Ploretarians Of The World Unite!"
most of them are us silver coins but one of these are mexican and french silver coins

the list of the coins
1851 mexican 8reales weight:27.073 grams fineness:0.9027 (the US dollar until 1873 was par to the mexican 8reales silver coin)
1828 french 5 francs weight:25 grams fineness:0.9
1833 US half dollar weight:13.48grams fineness:0.8924
1928 soviet 10 kopecks weight:1.8g fineness:0.5
1962,64 US half dollar weight 12.5g fineness:0.9.
1940,45,53 US quarter weight 6.25g fineness 0.9
1946,47,51,63 US dime weight 2.5g fineness 0.9

The US dimes and quarters and half dollars before 1964 are 90% silver
and only the half dollar in the 1965~1970 has 40% silver