The word bullion originally
meant ‘mint’ or ‘melting place’ from the old French
word bouillion (boiling) but became the generic term for refined
bars or ingots of gold and silver and the trade
in them. Thus, the Bullion Office at the Bank of England, by the eighteenth century,
was the crossroads of most gold transactions for the London market, just as many
traders call themselves bullion banks today.
Although principally implying bar gold, it has been
extended to cover bullion coins.