If it says "Ley 999" somewhere over its face, it should have an ounce of 99.9% pure silver.
A 1975 un peso coin from Mexico contains 10% silver, which is equivalent to 0.072 grams of silver. The rest of the coin is composed of copper and nickel. This coin is part of a series that was minted during a time when Mexico transitioned to a lower silver content in its currency.
1964 - $10 or so for the silver content (90% silver) 1965-1970 - $4.50 or so for the silver content (40% silver) 1971-present, 50 cents unless in mint packaging.
900 silver coin
If the coin is an "S" mintmarked silver proof coin, it's 90% silver.
There is no silver content in any general circulation British coin from 1947 onwards. The 10 Pence coin is made from 75% copper and 25% nickel.
90%
The silver content of the 1981 British Royal Wedding commemorative general circulation crown is zero. It is a cupro-nickel coin. No British general circulation coin has had any silver content since 1946. The 1981 silver Proof FDC Crown coin which was sold in a case, has a 92.5% silver content.
82.5% silver
Unless the coin is in a special holder that identifies it as a 40%-silver collector's coin, it's made of copper-nickel rather than silver and is only worth $1. As of 03/2011 a 40%-silver Ike might sell for at least $12 based on its silver content and the fact that it would be an uncirculated coin if it's still in its original holder
The last year for circulating silver U.S. dimes and quarters was 1964, while half dollars continued with a reduced silver content until 1971. Meanwhile in Canada, their dollars and halves were silver up through 1967, with quarters and dimes at a reduced content into 1968.
No S.B.A. coin was struck in silver, so the silver content is zero. All are copper-nickel.
About $3.25 for its silver content.