The larger pre-1993 10 Pence coins were withdrawn from circulation and demonetised in 1993. So, unless they are part of a Proof or uncirculated mint set or are individual Proof or uncirculated coins and in absolute mint condition, they have little or no value.
A British 1979 cupro-nickel 10 New Pence coin (Elizabeth II), uncirculated and in absolute mint condition could fetch up to £0.50 GBP.
A British 1979 cupro-nickel 10 New Pence coin (Elizabeth II)(Proof FDC), could fetch up to £2 GBP.
A reputable coin dealer will be able to give a more accurate valuation.
It's made of copper-nickel, not silver, and has no added value. Its exchange value is about 16 US cents as of 04/2013.
There were no British 1979 20 Pence coins minted.
2 British Pence in 1979 had the equivalent value of about 1 cent USD.
A British 1979 (silver) Twopence (Proof FDC), uncirculated and in absolute mint condition could fetch up to £20 GBP. A reputable coin dealer will be able to give a more accurate valuation.
Your description is applicable to every British coin issued in 1979. On the same side of the coin you read "New Pence", there will be a number indicating "how many" New Pence. The 1979 British 1/2, 5, 10 and 50 New Pence coins have long been withdrawn from circulation and have little or no value unless they are in mint condition, and even then, not much. The 1979 British 1 New Penny and 2 New Pence coins are still potentially in circulation, so are worth 1 and 2 Pence respectively, unless they are in mint condition, and even then, not much.
See the link below.
Still worth 50 cents. Unless its pure silver.
How much is a UK half pence worth
No coin exists. Silver eagles would not be minted until 1986.
The current price of silver is about $14/oz
Sacagawea silver dollar coins were not minted in 1979. The first year of issue for Sacagawea dollar coins was 2000, and they are made of a copper-nickel clad composition, not silver.
These coins are still potentially in circulation so, unless they are part of a Proof or uncirculated mint set or are individual Proof or uncirculated coins and in absolute mint condition, they are worth 2 Pence. A British 1979 bronze 2 New Pence coin (Elizabeth II), uncirculated and in absolute mint condition could fetch up to £0.15 GBP. A British 1979 bronze 2 New Pence coin (Elizabeth II)(Proof FDC), could fetch up to £1 GBP. A reputable coin dealer will be able to give a more accurate valuation.
How much is a UK half pence worth