METALS used in Roman Coins

GOLD coins are generally abbreviated as "AU" or even "AV".
The main gold roman denomination was the
aureus. Constantine replaced this with the solidus. Other gold denominations were the semissis, the scripulum and later the tremissis.
SILVER coins are generally abbreviated as "AR".
The main silver roman denomination was the
denarius. This coin lasted until the mid third century AD, when it was gradually replaced by the antoninianus. Later Roman empire silver coins are the argenteus, siliqua, miliarense.
AE coins, ie those coins abbreviated as "AE", are generally made of base metals, such as Bronze (an alloy of tin and copper), copper (a reddish metal) or orichalcum (a yellowish metal).
The main bronze denominations of the early empire were the
sestertius, the dupondius (orichalcum) and the as (Copper). Bronze coins in these days were usually issued by the Senate, and had SC (Senatus Consulto) on the reverse. Later both the denarius and the antoninianus lost their silvering and became bronze coins. The Later Roman Empire has the folles as its' main bronze coin, but there was also the centenionalis and numerous other nameless denominations now known as aes.