Yes, but none of the coins were made for general circulation. Silver Proof quarters sets and Silver Proof 10-piece sets were sold by the Mint, also the American Silver Eagle bullion coins were minted in 2006.
The US Mint did not issue any silver coins of any kind in 1980. If you have silver coins dated 1980, they are not US coins.
no to soft to make coins out of solid silver . .999% is the most silver in any coin .
Not a meaningful question. Gold coins were made from gold and copper without any silver in them. Silver coins were made from silver and copper without any gold.
The U.S. Mint did not issue a 1979 Silver Proof set. None of the coins contain any silver.
Zero. No New Zealand general circulation coin has had any silver content since 1946. The only exception to this is the 1949 and 1953 Crown (Five Shilling) coins. From 1947 to 2006, all New Zealand general circulation "silver" coins were made from a copper-nickel alloy. From 2006 onwards, all New Zealand general circulation "silver" coins were made from nickel plated steel.
Perhaps by a private mint but not by a government mint.
No current circulating US coins contain any silver at all. For information about older coins, please see the Related Question.
Yes they do. No British decimal general circulation coin has any silver content at all. The "silver" coins of all Commonwealth countries similarly have no silver content.
The U.S. did not make any dollar coins from 1936 to 1970 inclusive, so there aren't any coins in the date range you requested.
The U.S. did not make any $20 silver coins, look at the coin again and post new question.
You can because silver is not magnetic, however Most common day coins are not pure silver or any other metal.
1964 was the last year for any 90% silver coins struck for general circulation.