Before it was Grao Mogol, the settlement carried that mouthful of a colonial name - Serra de Santo Antonio do Itacambiracu - and it grew around the diamond diggings in the streams running down the Serra Geral. In 1839 it was renamed Arraial da Serra de Grao Mogol, an arraial being roughly the Portuguese equivalent of a mining camp with a church and a few shops. By 1840 it was elevated to Vila Provincial and became a formal district. In 1858 it received the status of cidade - city. Each promotion reflected a step up in the flow of diamonds, taxes, and population. At the town's peak the Portuguese crown was watching this corner of the sertao closely enough to take over the mining operations and the commercialization of the stones themselves.

The Igreja Matriz de Santo Antonio, the mother church in the center of town, was built in the nineteenth century. According to local and historical record, it was constructed by enslaved people, for the use of the white population. That sentence deserves to sit on its own. The diamond economy of Brazil, like the gold cycle that preceded it in Ouro Preto and the sugar cycle of the coastal plantations, ran on the forced labor of Africans trafficked across the Atlantic and their descendants. The stones that paid for those cobbled streets and the eighteenth-century facades still standing today were extracted - one pan of gravel at a time - by people who did not choose to be there and did not share in the profits. The churches they built are beautiful. The arithmetic behind them is not.

Alluvial deposits are easy to work and quick to exhaust. By the mid-nineteenth century, the easy gravels had been picked over, and Grao Mogol began the long quiet contraction that mining towns seem fated to undergo. In 1960 the municipality lost territory when Itacambira, Cristalia, and Botumirim were carved off as separate districts. The population thinned further. Today about 15,890 people live across a 3,890 square kilometer municipality - a low density even by the standards of the Minas sertao - and the elevation, 829 meters, keeps the town slightly cooler than the valleys below. Cattle and small-scale agriculture (bananas, coffee, corn, sugarcane) have replaced diamonds as the economic base. The soils are poor and drought is frequent, and the municipality's human development index has consistently ranked in the bottom third of Brazilian cities.

What remains in Grao Mogol is what tends to remain in small highland boomtowns everywhere: the architecture of the good years, and the landscape that shaped the money. The colonial buildings of the centro survived because there was no pressure to tear them down. Outside town, the Canyon do Extrema cuts through the hills - a gorge of plunge pools and waterfalls that is now the reason most visitors come. Beyond it, the 28,404-hectare Grao Mogol State Park, created in 1998, protects Cerrado uplands and canyons and a considerable variety of endemic plants. The park, in its way, closes a circle: what was stripped for gemstones two centuries ago is now protected because of what grows on it. An hour's drive south sits Itacambira, also carved off from Grao Mogol, also poor, also beautiful. The Jequitinhonha River winds through the valleys below, still carrying sand and the occasional stone, still giving up the occasional diamond.