The La Frontera property is a low sulphidation style silver-gold prospect located 320 kilometres west southwest of the City of Salta, northwest Catamarca Province, Argentina. Access is by 75 kilometres of rough 4 x 4 or quad trail from the south end of the Salar Rio Grande.
Mineralization at La Frontera is of the low-sulphidation (quartz-adularia) epithermal type within Tertiary felsic volcanics. Metals of interest are dominantly silver with subordinate gold. Sulphide content is very low with minor pyrite and chalcopyrite noted. Thin section work has shown argentite to be the main silver bearing species present. Areas of exposed and inferred mineralization cover an area exceeding 1,500 metres in length.
In several trenches, high-grade mineralization occurs at the end of the trench, suggesting that the mineralization may be wider than currently indicated. The results of the more significant mineralized intervals are summarized below.
In addition, sampling on a separate zone (Amethyst Zone) located one kilometre northwest of the main mineralized trend has returned erratic yet significant values of gold and silver. In excess of 80 samples were assayed with values ranging from nil to 4.3 g/tonne Au and from nil to 43 g/tonne Ag. The Amethyst Zone comprises an area of intense stockwork and sheeted quartz-adularia veining which measures 250 metres by 300 metres. Geological elements suggest the Amethyst Zone may represent a low-grade silica cap above higher grade mineralization at depth.
2000: Mineralization at the La Frontera property was initially discovered and staked by Mansfield’s exploration team in March 2000. There was no evidence of previous exploration in the area.
2005-2007: Apex Silver Mines Ltd. completed trenching and 2,150 metres of core drilling in 12 holes under an option agreement with Mansfield Minerals. Apex Silver Mines dropped the option in 2007.
2008: The El Camino property was transferred to Pachamama Resources Inc. as part of a restructuring of Mansfield Minerals Inc.
2012: The property was transferred to Regulus Resources Inc. as part of the merger with Pachamama Resources Inc.
Between September 2006 and February 2007, Apex Silver Mines Ltd. completed 2,150 metres of core drilling in 12 holes under an option agreement with Mansfield Minerals. See below for a summary of the most important results of that program.
|North Trench||6.2 m||0.60||2344.0||71.00|
|Trench II||38.0 m
incl. 10.0 m
|Trench VIb||24.0 m||0.60||18.0||6.30|
|Trench V1a||6.0 m
and 2.0 m
|Breccia Sur||14.0 m
incl. 2.0 m
|Drill Hole Number||Interval||Width||Gold (ppm)||Silver (ppm)|
|LFD-001||147-149 m153-172 mincl. 169-172 m||2 m19 m3 m||0.550.291.27||50.0099.00283.00|
|LFD-002B||84-85 m||1 m||–||51.00|
|LFD-004||86-87 m113-114 m120-121 m
|1 m1 m1 m
|LFD-007||87-89 m91-93 m||2 m2 m||0.610.85||18.003.50|
|LFD-008||27-30 m48-53 m||3 m5 m||-0.99||63.0052.60|
|LFD-010||60-89 mincl. 70-71 mincl. 80-81 m
|29 m1 m1 m