Published online by Cambridge University Press: 02 January 2015
The name Riotinto has something of a magical connotation in the world of mining. It has been called the geologist’s paradise because at almost no other place on the earth has nature exposed in one spot such richness and variety of minerals. The floor of the bed of the richest areas in Riotinto is made up of a mass of porphyry and pyrites overlain by an oxidised cap. At the zone of contact between the two levels is an enormous deposit of silver, gold and other metals which today, as in ancient times, supports a flourishing industry.
* The term ‘jarosite’ used in this context is somewhat misleading. Many metallurgists today use the word to describe any ore rich in this mineral. Since it is far from pure jarosite, the ore in this instance would be better described as ‘jarositic earth’. For a more detailed discussion of these ores from Riotinto see Allan, John C. in Bull. Hist. Metallurgy Group, 2 (1968), 47–50 Google Scholar.
Some metallurgists may doubt that there existed any need to add either a flux or lead, as suggested in this paper, to effect the separation of the metals present in the ore, on the grounds that the jarositic earth, as the chemical formula of jarosite shows, was already rich in potash. Equally lead, in the form of plumbo-jarosite, was present in the ores in appreciable quantities, as shown by the analyses listed by Allan (op. cit., 48, table).—Editor.