All British Halfcrown coins, up to but not including 1920, were made from sterling silver (92.5% silver).
All New Zealand Halfcrowns from 1933 to 1946 inclusive, had a silver content of 50%. From 1947 to 1965 inclusive they were made from copper-nickel.
Zero silver content. All general circulation Irish "silver" coins minted since 1951 have been made from a copper-nickel alloy.
All Eire (Irish) Florins from 1928 to 1943 inclusive had a silver content of 75%.
Such a coin does not exist. The last Eire (Irish) Halfcrown was issued in 1967. The Halfcrown was withdrawn and demonetised after the introduction of decimal currency in 1971.
An Eireann (Irish) 1930 75% silver Halfcrown (horse), uncirculated and in absolute mint condition could fetch up to £495 GBP. If it has been circulated but still in good condition, it might fetch anything from £12 to £130 GBP. An Eireann (Irish) 1930 75% silver Halfcrown (horse)(Proof FDC), uncirculated and in absolute mint condition could fetch up to £1,000 GBP. A reputable coin dealer will be able to give a more accurate valuation.
All British Halfcrown coins from 1816 up to and including 1919 were made from sterling silver or .925 fineness.
British 1913 Halfcrown coins were minted in 92.55% silver only
No. The 1970 British Halfcrown was minted as a Proof FDC coin only in cupro-nickel.
No. All British Halfcrown coins prior to 1919 were made of almost pure silver. In 1947, all British silver coins were from then on, made of cupro-nickel.
An Eire (Irish) 1959 cupro-nickel Halfcrown (horse), uncirculated and in absolute mint condition could fetch up to £45 GBP. If it has been circulated but still in good condition, it might fetch anything from £2 to £12 GBP. An Eire (Irish) 1959 cupro-nickel Halfcrown (horse)(Proof FDC), uncirculated and in absolute mint condition could fetch up to £750 GBP. A reputable coin dealer will be able to give a more accurate valuation.
There is no silver in any British general circulation coin from 1947 onwards.