Most New Zealand "Proof" One Dollar coins from 1974 onwards are made from sterling silver. Those that are not made from silver are made from an aluminium-bronze alloy.
If they are made from silver, it should be stated on the packaging they are sold in.
The only Kennedy half-dollars after 1971 to have any silver are in Bicentennial (40%) silver Proof and Unciculated sets sold from the Mint. In 1992 the Mint started making "Silver Proof" sets again with 90% silver coins.
Proof and uncirculated versions were made from 1971-1976, none were made for 77-78
In general circulation US coins, the 90% silver coins were last made in 1964. Some proof sets made later contain more silver than the general circulating coins. The Peace dollars made 1921-1935 were the last 90% silvers, some Eisenhower dollars made 71-76 were 40% silver.
All circulating quarters dated 1965 and later are made of copper-nickel, and don't contain any silver. The only circulating coins that were made of 40% silver were half dollars from 1965-1969. Proof and mint-set 40% silver quarters, halves, and dollars were struck for the Bicentennial and carry the dates 1776-1976. Other dates of 40% silver Eisenhower dollars were also struck for proof and mint sets.
None that are made for circulation contain any silver. However, some special proof coins made for collectors DO contain silver. The same goes for dimes and half dollars as well.
The last true silver dollars were made in 1935. That year marked the end of 90% silver dollars. The next silver dollars were made in 1971. These were Eisenhower dollars. They are not made of silver but rather of copper and nickel.
Half dollars have never been made out of pure silver but all half dollars minted before 1965 are 90% silver, halves dated 1965-1970 are 40% silver. Circulation issue halves dated 1971 and later are copper nickel and thus worth 50 cents. The US still makes commemorative half dollars such as the 90% silver proof half dollars made from 1992-present.
Dimes dated 1964 and prior are 90% silver. Dimes dated 1965-present that are intended for circulation contain no silver. From 1992-present the US has made silver proof sets which contain a 90% silver dime along with 90% silver quarters and half dollars. Keep in mind though that it is only the silver proof set that contains silver, the normal proof sets do not (unless the coin intended for circulation had silver)
In the U.S., the last year for circulating silver dimes and quarters was 1964, and half dollars until 1970 (at a reduced silver content). Nickels dated 1942-1945 contained 35% silver, as nickel was needed for the war effort. Production of silver dollars ended in 1935. Some Eisenhower dollars and modern proof dimes, quarters, and half dollars are made with silver, but those versions are specially made for collectors rather than general circulation.
Circulation Ike dollars were made of copper-nickel, not silver. They're only worth face value to $1.10.Uncirculated ones might retail for a couple of dollars.40% silver collector's versions were also made. These retail for anywhere from about $5.50 to $15.00 depending on date and whether they're in uncirculated or proof condition.
No 1972 silver proof sets were made, only single Eisenhower uncirculated & proof coins were struck in 40% silver.
Are silver coins made by the US Mint. Quarters, Dimes, Half dollars and dollars struck for circulation dated 1964 and prior are 90% silver. Half dollars dated 1965-1970 are 40% silver. All US coins intended for circulation dated 1971 and later are not silver. The US has and does mint silver coins intended for collectors including the American Silver Eagle, since 1992 they have made a silver proof set and there have been many silver commemorative coins minted.