A coin tree is the original post-casting state of Chinese cash. When coins
are cast, copper is flowed into a mold via "drain passages" that
end up at the coin imprint. When the copper has solidified, the mold is
removed and the filled "drain passages" are the trunk and branches
of the tree and the coins are at the far end of each branch. Hence the term
"coin tree". After the tree is formed, mint workers will pluck
off each coin and file the edges smooth and surfaces flat to reveal the
characteristics of each coin.