In addition to the latter, to the east are two concentrations called Planes and San Antonio, which Atalaya Mining is studying for exploitation.

Another large independent adjacent concentration to the west is Masa San Dionisio, which is the unmined part of Corta Atalaya.

Within this area there was an unexploited deposit, Cerro Colorado, whose mass consisted of low-grade copper ores and was covered by a gossan overburden.

[3] This ferruginous overburden contained significant amounts of gold and silver, while the stockwork mineralisation had a high copper content.

[4] In 1966, the Rio Tinto Patiño company was formed to explore and mine Cerro Colorado,[5] with the first work commencing in 1967.

From 1968 onwards, a significant part of the basin's mining and mineralogical activities were concentrated at Cerro Colorado,[6] in contrast to the decline of other deposits.

Over time, the mineral reserves of the deposit increased with respect to the initial estimates due to the research work carried out in old mines in the area, such as Filón Sur, Quebrantahuesos or Cerro Salomón.

In 1995 the deposit passed into the hands of the labour corporation Minas de Río Tinto (MRT), which kept it in operation for several years.

With the current proven and probable reserves, Cerro Colorado will be 2400 m long, 1250 m wide and have a maximum depth of 335 m when it reaches the end of its life.