The hills of Zaruma and Portovelo have been mined for gold and silver for centuries. The Incas were already extracting gold and silver in
the area with hydraulic mining of the oxidized parts of veins when Mercadillo, one of Pizzarro´s force, followed the Rio Amarillo River
upstream and encountered the Inca mine and founded the town of Zaruma in 1549 (Billingsley, 1926). Exploitation of the Zaruma and Portovelo
districts continued during the time of Spanish colonization until 1870 when an Ecuadorian-Chilean company was established. In 1880, Grant
Zaruma Company, from England, bought controlling shares of a newly-formed Ecuadorian-Chilean mining company. Operational rights were
immediately endorsed to Southern American Development Company (SADCO), an American company, who operated the mine from 1897 to 1950 by
gaining control of the district’s main gold deposits in 1897.
The Miranda mine was originally owned by a mining individual who held ownership of the property for over thirty years. Some rudimentary tunnels and mining activity took place over this period, but no significant volume of ore was extracted. In the beginning, Compañia Minera PL S.A utilized the existing mining works, tunnels, raises, and shafts to access the gold bearing veins. These tunnels have been improved by the utilization of advanced engineering technology to serve the mining requirements of the company.