When the colonists did encounter coins, it was likely to be Spanish. Spain controlled virtually all of the silver and gold production in the new world and I think but might be wrong, a little under half of the world's silver supply. Under the period Mexico was a Spanish colony, Mexico city churned out hundreds of millions of pesos. Each peso was equal to 8 reales and the hundreds of millions of pesos was probably a mixture of the all the denominations minted. There were other mints like in Lima and Potosi and at certain points they could rival the high production rates in Mexico City.