La Compañía Minera de Sierra Menera Historical milestone · Ojos Negros, Jiloca, Teruel Around 1900 the Compañía Minera de Sierra Menera industrialised the extraction of iron over a deposit of some eighty million tonnes. The population reached its historical maximum in 1910 and the working ceased in 1986 with the steel crisis. 1900-1986 Photo: Julen Iturbe-Ormaetxe (CC BY-SA 2.0) What to see and do in Ojos Negros