Santa Juana Mine
Access to the Santa Juana mine is via a 1,400 metre cross-cut from the Terneras portal to the deck of the Santa Juana winze. This access is located on the 6th Level of the Terneras mine, which corresponds to the 12th Level of the Santa Juana mine. The winze, which is approximately 200 metres below surface, allows access from the 12th Level to the 17th Level. A ramp has been driven from the 15.5 Level (which corresponds with the 1,400 m elevation above sea level (ASL), 500 metres below surface) to the 18.5 Level and extensive development has been completed on this level. Also a new area has been developed east of the Tres guilas fault and is known as the Tres guilas sector of the Santa Juana mine. A new ramp reached the 18.5 Level in this sector and, currently, extensive new workings are being opened on Levels 15 to 18 in order to better define new geological concepts.
The Terneras mine is accessed on the 6th Level via the Terneras portal. The Coronillas shaft also provides access to the 1st Level of the mine. The La Chona adit, at an elevation of approximately 1,880 metres ASL, provides access to Level 5 of the La Chona portion of the deposit.
The main accesses to the San Juanes vein are from the Terneras 6th level and from an adit one kilometre from the Terneras adit which gives access to the 1st level. Additionally, a 50 metre long drift and a 20 metre deep shaft are connected to the surface in the Coronillas area.
The San Mateo vein was primarily mined by gambusinos. Nevertheless, by 1939, in the main shaft area, the vein had been mined from surface to the 12th level. Accessible workings along the San Mateo vein consist of the Santa Rita mine that allows access to the 3rd level by a shaft; the adit of the Santa Teresa mine on the 2nd level of San Mateo; the adit of the La Estela mine on the 1st level of San Mateo, and a cross cut reaching the 6th level from the main Terneras adit with drifts being opened on that level by ECU.
On the San Diego concession block, historical workings are known on the La Cruz and the El Trovador veins. Along the western portion of the La Cruz vein, the La Cruz shaft was sunk vertically for about 80 m from the approximate elevation of the 3rd level, whereupon it becomes inclined. To the east, the Los Adelaidos shaft is vertical for a depth of 115 metres. Two shafts are also present along the El Trovador vein. The western shaft is approximately 165 metres deep, whereas the eastern shaft connects the 360 metre long Viboras adit to a level located 75 metres below.
Historically, the most important developments were conducted on the Chicago vein which crosses the Los Muertos, Chicago, Santa Teresa and San Juan concessions. The majority of the old workings were done on the Los Muertos concession where three levels were opened, up to 370 metres in length, with shafts sunk to a depth of 215 metres. The access to lower levels was through a 145 metre inclined shaft connecting Level 2 to surface. Numerous other shafts and pits were sunk all along the structure but without significant mining workings.