This dataset, kindly provided by Professor Richard Garner, contains accounting information from the Royal Treasury offices for the Spanish Empire Colonies (from 1570 to mid 1800s). There is also information related to mercury supply for the mining industry in the colonies and gold and silver registration statistics compiled by Jonh TePaske.
The website is maintained but not updated. For further information please contact Prof. Richard Garner. You can also follow him on Twitter.
Link: CAJA FILES