On another note, a lot of the Silver mined in Spanish Colonies actually never was sent to Spain, a lot of the treasure fleets directly sailed for the Philippines for a period, because Spain used a lot of the silver to trade with China anyway.

John Gareth Darwin talked about this in _After Tamerlane_, called the [Manilla Galleons](http://en.wikipedia.org/wiki/Manila_galleon) for the harbour they used, sailed for ~250 years from Manila to America between 1565 & 1815.