Besides the mountain towering over the city of Potosi, the Casa de la moneda is, in my opinion, the second biggest attraction. It was here that all the silver, extracted from the mountain, flowed through on it’s way to Spain, and the world. The original building was build along side the center square in 1574, but when production became too much for the mint to handle, a new mint was built in 1759. This second mint is where tours are held. An extensive collection of coins, machines, and dioramas highlighting the workings of the mint from the manual slave era, though the steam era and into the modern day electrically driven production lines.
The tour started in a room which exhibited hundreds of coins minted in Potosi throughout it’s 400 year production run. Many of the old coins were squared off because the value was in the silver and not in the actual coin. Therefor pieces were often cut off of the soft metal to divide the value of the coin into smaller amounts. The guide explained the immense impact this mint had on the world as it was considered to be the makers of the first globally recognized currency. When the newly formed United States was producing ‘IOUs’ in the for of paper money, it also circulated silver coins from Potosi known as Spanish dollars. It was from this mint that St Peter’s Basilica was financed, and due to Spain’s senseless spending, most of the wealth exiting the mint profited much of Europe and Asia as well. Also, it is argued that the modern day dollar sign originated from the superimposed lettering PTSI mint mark (short for PoToSI) which was later reduced to SI or $.
After the first room, we moved on to a room featuring huge old wooden machines used to flatten the silver bars to the proper thickness as well as punch out the coin blanks. Because of the dry climate in Potosi, the original 300 year old oak, mule driven machines are still in perfect condition. They were shipped across the ocean to Buenos Aires, then along a 14 month mule train up into the highlands of Bolivia where they still sit today as the last existing machines of that era.
On a lower level we saw the stalls where mules were attached to carousels and worked for 12 hours a day walking around and around powering the silver working machines. Horses were originally used but were unable to cope with the 13 000ft altitude of the city. Mules took their place, but even they would only last 4 months before dropping dead. Wikipedia later informed me that 20 slaves later took the place of the 4 mules per machine.
Further along in our tour we were brought to a room which held the equipment and dies which men would use to manually strike the blanks of silver and imprint the logos. Each worker was expected to strike 1000 coins a day. A later invention called the screw press took its place. This machine took a minimum of 3 men to operate and resulted in a more consistent imprint, and the occasional loss of fingers for whoever has the job of placing the blank in the machine. A 10hp steam powered locomotive engine the size of a mini bus replaced the mule and slave powered machines, which was in turn replaced by the electric engine.
We were taken to a room where the crude silver bars were cast. The ore was mixed with mercury to separate it from impurities, and then was heated until liquid, and poured into rectangular castings. It was said that this was the most dangerous job in the mint due to the toxic gases given off from the heated mercury. Looking up, you can still see the blackened ceiling from the constant smelting fires.
Production in the mint halted in the 1950s and from that point on the or was shipped internationally in crude form, and the building was converted into a museum, with all machines left in their original places. Going into the tour, we thought it would just be something to pass the time, but left very impressed and slightly more knowledgeable about a piece of history.