their labours. Attempts to introduce systematic mining have been made by the Government, but without success...different angles ; and in various parts of the district they differ materially in thickness. Several beds...their walls, it is disseminated through (the Manto de Ossa) certain upper layers of the first limestone...unproductive (cross-) veins, which traverse the district, differ materially from most, yet nearly coincide...passing from the cellular limestone of the Manto de Ossa into the compact rock beneath, the lodes-diverging |