Note 307 — Chapter XII
Reading edition
On the Geology of Bolivia and Southern Peru, by David Forbes, Esq., in the Journal of the Geological Society for Feb. 1861, p. 53.
Mr. Forbes had, of course, personally examined only a portion of this great Silurian region. At Tipuani, in Bolivia, there is a very rich auriferous country, composed of blue-clay slates, with no fossils; while the beds near Sorata contain fossils, and consist of blue-clay shales, micaceous slates, grauwacke, and clay slates, with gold-bearing quartz, metallic bismuths, iron-ore, and argentiferous galena. "The whole of this Silurian formation is eminently auriferous, and contains everywhere frequent veins of auriferous quartz, usually associated with iron pyrites."