Between Ouro Preto and Mariana lies Brazil's oldest gold mine. During the gold rush thousands of slaves perished at Mina de Ouro de Passagem because of its dangerous, backbreaking conditions. Although the mine is no longer in operation, you can ride an old mining car through 11 km (7 miles) of tunnels and see exposed quartz, graphite, and black tourmaline. Buses travel here from Ouro Preto (catch them beside the Escola de Minas) and cost about R$3; a taxi ride costs about R$30.
Road to Mariana, 4 km (3 miles) east of Ouro Preto, Mariana, 35420–000, Brazil