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.