DISCUSSION. MINING METHODS PAST AND PRESENT IN THE MORRO VELHO MINE OF THE ST JOHN DEL REY MINING COMPANY, LTD., AND LODE-CHANGES WHICH HAVE NECESSITATED AN ALTERATION OF SYSTEM.

Keywords: ST JOHN DEL REY MINING CO, MINING, METHODS, ORES, MINES, VENTILATION, PITS, FILLING, TEMPERATURE, COOLING, SHAFTS, TUNNELS, COSTS, THICKNESS, WALLS, MINERALS, LABOUR, RIO DE JANEIRO, MORRO VELHO, BRAZIL, SOUTH AMERICA