La Esperanza
Quick Facts
Location:
Santa Cruz Province, Southern Argentina. 900m elevation.Ownership:
Andean is currently earning a 100% interest in La Esperanza through an Option Agreement.Mineralisation:
Low-sulphidation, epithermal gold (and potentially silver) hosted within quartz veins and associated stockworks with potential bonanza type grades.
The three properties - San Augustin, La Esperanza and Las Mellizas - are all located in a regional cluster approximately 100km to the southwest from Cerro Negro, in the province of Santa Cruz.
Access to all of the properties is good, via a series of good hard-packed tracks easily navigable, in dry weather, with 4-wheel drive vehicles. All of the properties are accessible, to the south, from Ruta 39 that connects Las Heras and Bajo Caracoles, via the access entrance to the Cerro Negro property.
Initial exploration by Pegasus Gold proved sufficiently encouraging for them to drill 17 reverse circulation holes (506m). In 1998 the property was joint ventured to IAMGold who completed further mapping, geochemical sampling, trenching (>5,000m) and 23 core drill holes (4,153m). The results of this work has identified what has been described as a classic epithermal system centred on the Cerro Guanaco domal feature, and with the Cerro Tornillo breccias, the T7 Vein and Veta Sur vein structures representing different levels within the epithermal system.
The upper part of the system is best seen on Cerro Tornillo, where low-grade gold values (< 100ppb) and anomalous Hg and Sb were tested by 10 holes. The best intercept was 3m @ 0.44g/t Au, including 1m @ 0.61g/t Au. It is considered that Cerro Tornillo as a "lithocap" to the system and not a target for near-surface economic grade gold mineralization.
About 1km to the south, and extending north from Cerro Guanaco, the T7 structural zone is about 500m wide and 2km along strike with intensely altered volcanics, and some vuggy quartz. Trenching across this altered zone has given some significant values, as for example 7m @ 19.8g/t Au (T7), including 1m @ 121.7g/t Au, and 12m @ 0.89g/t Au (T9). Drill testing of these, and other trench intercepts, did not confirm the continuation to depth of equally intensive values. Sampling conducted by Andean indicates that the T7 Structure mineralization has a Au-Ag-Te association with values up to 30.97g/t Au, 30.19g/t Ag and >2,000g/t Te.
At Cerro Guanaco itself, the dacitic intrusive is considered to be a target for exploration. It is noted that such intrusives are, on occasion, associated with large gold deposits in other districts.
A further 2km to the south-southwest, Veta Sur, is a 1.5 - 2km northerly striking, 1 - 3m wide, quartz vein and stockwork system. The only drill hole testing this structure intersected 1.45m @ 1.2g/t Au.
Veta Sur, look north, with the one drill hole collared in the middle ground to the right.