If you're referring to a U.S. cent, they were all made of bronze from mid-1864 to 1942 and again from 1944 to the middle of 1982(*).
That means there are hundreds of possible coins to choose from so more information is needed - the date, and if the coin is dated 1908 or later, whether it has a mint mark. To find the mint mark on a 1908 or 1909 Indian cent, look on the back under the wreath to see if it has a small "S". On Lincoln cents, look under the date for a D or S. Any cent that doesn't have a mint mark is normal, it was simply made in Philadelphia.
(*) To fill in the gaps, cents were made of steel in 1943 to save copper for the war effort, and the composition was changed to copper-plated zinc in 1982 because copper had become too expensive.
a cent
a penny
A bronze penny has a reddish-brown color due to its copper content, while a zinc penny has a silver appearance. You can also check the date on the penny, as pennies made before 1982 are bronze and those made after are zinc.
Bronze
All 1967 general circulation British Pennies were made from bronze. If you have a silver Penny, it will be because somebody has plated it. Alternatively, the British Maundy Penny is a very much smaller coin than the traditional Penny and is made from sterling silver.
From 1860 to 1967, the British bronze Penny was 30.81 mm in diameter.
For many years up to and including 1792, the British Penny was silver. From 1797 to 1860 inclusive, the Penny was copper. From 1860 until its last minting in 1967, the Penny was bronze. From 1971 to 1992 inclusive, the decimal (New) Penny was bronze. From 1992 to present, the decimal Penny has been made from copper plated steel. The only British decimal coins with any brass in the alloy are the One and Two Pound coins.
Brass? No. Bronze yes. A few bronze 1943 Lincoln cents were made by mistake.
All British bronze Pennies from 1860 to 1967 have the words "ONE PENNY" on the reverse.
The dimensions of the New Zealand Penny was very similar to the British, Australian and other Commonwealth country Pennies. It was made from bronze, was 31 mm in diameter and weighed 9.45 grams.
In 1903, the U.S. penny was made of bronze, which is an alloy of copper (95%) and tin (5%). The penny continued to be made of bronze until 1982 when it was switched to a copper-plated zinc composition.
All Lincoln Wheat penny's from 1909 to 1942 were made from Bronze .950 copper and .050 Tin and Zinc.