Gold and silver mineralization on the Pinos Altos property consists of low sulphidation epithermal type hydrothermal quartz veins, stockworks and breccias up to 40 metres in thickness. The most significant mineralization on the property that has been the site of historical mining activities and on which the Pinos Altos mining project is centred, is located in the southeast part of the property. It consists of four mineralized zones, up to 500 metres long by up to 700 metres deep, that are hosted by the Santo Niño structure over a distance of almost 5 kilometres and named from east to west: El Apache, Oberón de Weber, Santo Niño and Cerro Colorado. The San Eligio zone, located approximately 500 metres northeast of the Santo Niño Zone, and within the horst structure, also comprises the Pinos Altos mining project.

Elsewhere on the property, significant gold and silver mineralization also occurs near or adjacent to the north side of the horst structure, namely the Reyna de Plata zone (along the Reyna de Plata Fault) located 1 kilometre north of Santo Niño and 5 kilometres further to the northwest, the Madroño and Carola prospects, which have also had previous mining activity.

Pinos Altos is a series of open pits and an underground mine along the Santo Niño Fault. Surface mining is carried out at the Santo Niño and San Eligio pits, and, in future, the El Apache pit. Mining is by conventional open pit methods, using shovels and trucks to remove about 5 million tonnes of ore and waste in 2016, and about 2 million tonnes of ore and waste per year in future years. The underground mining method is sub-level stoping (paste backfill) to extract ore from the Santo Niño and Cerro Colorado deposits. The shaft project for hoisting underground ore was completed in mid-June 2016, with ramp-up to the design capacity of 6,000 tonnes of ore per day completed in July.

Most of the Pinos Altos ore is treated in a processing plant, with the lower grade ore heap-leached. The conventional, 5,500-tonne/day process plant includes crushing, grinding, gravity concentration and agitated leaching followed by counter-current decantation. Gold and silver are recovered using the Merrill-Crowe method, and a refinery produces gold/silver doré bars on site. Metals recovery in the plant is estimated at 94% for gold and 44% for silver over the life of the mine. The lower grade Pinos Altos ore is treated in a heap-leach system designed to accommodate 5.6 million tonnes of material over the life of the mine, contributing about 4.3% of the total metal production.