Thin air, thick silver
You are fourteen years old and you live in one of the highest cities on Earth. Climbing a staircase here leaves you gasping. Water boils before it is properly hot. Nothing grows — no wheat, no fruit, barely a blade of grass. Fifty-five years ago there was no town here at all, only wind and a red mountain the Quechua-speaking people called Sumaj Urku.
Now there are more people here than in Madrid or Rome. Silk from China hangs in the shops. Olives arrive from Seville, sugar from Brazil, iron from Vizcaya, coca leaf by the mule-load from the warm valleys. Everything you eat and wear was carried up to you by llama and mule, because everybody in the world wants what comes out of that mountain.
Your job starts before dawn at the Casa de la Moneda — the royal mint. You weigh silver. You shave a coin blank until a balance beam sits perfectly level. Then somebody swings a hammer, and a disc of metal becomes money that will travel further than you ever will.
The mountain, opened
Before the silver can be money, six different worlds have to touch it. Tap each glowing point.
Tap the glowing points on the mountain
The wind ovens (guairas)
Andean smelters got here first. Their guaira was a clay chimney full of holes, packed with ore and llama dung, set on a ridge so the katabatic night wind blew through it like a bellows. On a good night thousands of them burned across the slopes at once — a mountain lit up like a sky turned upside down. This technology was Indigenous, not Spanish, and for the first 25 years it did nearly all the work.
Your bench at the mint
A piece of eight is not a design. It is a promise about weight and purity: 8 reales, about 27.5 grams, roughly 93 parts silver in 100. Your job is the weight. Cut a blank, shave it to the mark, then strike.
Real mint workers did this thousands of times a day, by feel.
Follow the coin
Nothing about this coin stays local. Pick a route and watch where your morning's work ends up.
The arbitrage bench
Around 1600 one unit of gold bought about 12.5 units of silver in Seville — but only about 6 in Canton. Silver was simply worth twice as much in China. So merchants shipped silver east and brought gold back.
This is why a mountain in the Andes was emptied to pay taxes in China: the Ming state had just ordered its taxes consolidated and paid in silver, and China had little of its own.
Silver bought per unit of gold, 1580–1660
The gap is the profit. Ships kept sailing until the two prices met — by about 1640 the world had one silver price. That convergence is one of the first things historians point to when they argue that globalisation began here. Figures are approximate, reconstructed from merchants' reports.
The line that never left
The draft had a hard edge. If your village lay inside the boundary drawn in 1573, your men were taken; a day's walk outside it, they were not. The system ended in 1812. The line did not.
Drag the marker across the old boundary
Why would a 200-year-dead law still show up in a household survey? The leading explanation is that draft districts were deliberately kept free of large private estates, so after independence they got fewer land titles, fewer roads and less schooling — and roads and schools compound for centuries.
What the ledgers do not count
You will read that eight million people died inside Cerro Rico. No historian can support that number, and no one can give you a true one — the burial books are patchy and the mountain never kept a tally. What is documented is bad enough: mercury poisoning, lungs destroyed by dust, cave-ins, a draft that took a man for a year and often kept him longer through debt, and whole villages that emptied because leaving your home province was the only legal way to escape the list.
A letter to the king
In 1615 an Andean nobleman, Felipe Guaman Poma de Ayala, finished a 1,189-page illustrated letter to King Philip III describing what colonial rule was actually doing to his people — including Potosí, which he drew. The letter never reached the king. It surfaced in a Copenhagen library in 1908, and it is now one of the most important sources we have.
Five centuries in one line
Drag the handle, or tap a marker
Silver is found
By tradition an Andean prospector, Diego Huallpa, finds silver on the slope. Within a year a town of tents exists at 4,000 m.
The assayer's examination
Seven questions. No half marks at the mint.
Six things to carry away
- Potosí was probably the largest city in the Americas around 1600 — and there is no farmland anywhere near it. Every loaf of bread had to be carried uphill.
- The dollar sign most likely comes from this coin: the two Pillars of Hercules wrapped in a ribbon, printed on the back of the piece of eight.
- "Vale un Potosí" is still ordinary Spanish for "worth a fortune", 480 years later.
- Spanish pieces of eight circulated so widely in Asia that Chinese merchants stamped them with their own marks — you can buy coins today carrying both a Spanish king and a Cantonese banker's chop.
- The lagoons Toledo's engineers built in the 1570s still supply water to the city of Potosí.
- Miners still leave offerings for El Tío at the tunnel mouth before every shift — a ritual older than every country in the Americas.
Try this at home: the arbitrage game
You need two players, a handful of coins (or dried beans) and two bowls labelled SEVILLE and CANTON. Write on a card: in Seville, 12 silver = 1 gold; in Canton, 6 silver = 1 gold. Player A starts with 24 silver. Trade them in Canton for 4 gold, carry the gold to Seville, trade back for 48 silver — you have doubled your money by moving, not by making anything. Now play a second round, but each time silver crosses the table, remove one coin as the cost of the voyage, and let the Canton rate creep up by one every round: 6, then 7, then 8. Keep going until the trade stops paying. The round where it stops is roughly what happened to the real world around 1640.
Talking point while you play: nobody in this game is mining anything. Where did the wealth actually come from?
One last question
Your coin leaves Potosí as a promise about weight. It crosses two oceans, gets a Chinese merchant's stamp hammered into the king's face, pays a farmer's tax in Fujian, and 200 years later buys a loaf of bread in Boston. Nobody along that chain has ever seen the mountain, or the men who carried the rock out on their backs. So: when you hold money, whose work are you holding — and how would you ever know?