Describe the composition of a coin?
It's not clear what you're asking. Coins are normally composed
of metal, sometimes mixed together as an alloy, sometimes in layers
like US clad coinage, and sometimes in bimetallic coins with a
center of one metal and an outer ring of another like Canadian $2
and EU €1 and €2 coins.
If you're asking specifically what metals coins are made of that's much more complicated to answer because it depends on the country that issued the coins, what denominations and often what year the coins were made. If so please post a new question with more specific details.
To describe a coin, assuming you can't read the Chinese, you would give a couple of pieces of information. Number one would be the composition, is this coin bronze, silver, gold, aluminum, steel? Number two would be the weight. Number three would be the diameter. And number four would be what the coin looks like, does it have a hole in the middle, a picture of someone, etc. If you are on a site that…