Summary:
The Bethania silver deposit is a polymetallic (Ag-Pb-Zn-Cu-Au) hydrothermal deposit whose mineralogy, mineralization, textures, and associated alteration phases are consistent with the intermediate sulphidation (IS) epithermal geological model for volcanic-hosted precious metal deposits.
The Santa Elena mining concession covers Tertiary volcanic rocks that include andesite, dacite, and tuff. Outcrop exposure is best in areas of higher elevation (high cliffs, hill tops etc.) and along road or stream cuts, with much of the region covered by vegetation and Quaternary deposits (overburden).
All of the mineralized veins discovered to date are hosted by altered andesite and/or dacite with some anomalous mineralization hosted by siliceous bodies of stockwork quartz-breccia. The attention of past on-vein exploitation focused on the east-northeast trending veins but there are numerous north-northwest trending veins that have seen little if any exploration and testing.
The total lengths of the vein systems are not clear for all the veins and there is evidence that the northeast-trending veins (e.g., Española and Carolina) could extend several hundred meters along strike. In addition, many of the veins continue at depth as evidenced from underground mine development and the recently completed Phase diamond drilling program.
Ausenco (2017), noted that geochemical results indicate the potential for an igneous body of the copper porphyry type existing at depth, suggesting the possibility for deeper copper dominant mineralization. Work in the immediate area of the Santa Elena concession provides evidence for a porphyry system underlying the area including drilling by Minera IRL Limited. Furthermore, satellite imagery suggests that the Bethania Mine and Santa Elena mining concession vein system are almost central to what appears to be a wide zone of alteration sitting centrally within what appears to be an 11 km wide collapsed caldera, indicating a much bigger exploration target both laterally and at depth. There are similarities here with the 15 km wide collapsed caldera that surround the San Genaro and Reliquias mines 70 km to the south of the Project.
There are a number of high-angle, northeast-, northwest-, and north-south-trending fault systems on the Santa Elena concession. Principal veins of economic interest are oriented east-northeast (~60Az) and dip from approximately 70 degrees to the southeast to near vertical.
Hydrothermal alteration observed on the Property includes silicification, sericitization, chloritization, and tourmalization, with silicification immediately associated with economic vein mineralization. Argillic alteration (clay) occurs away from the veins and chloritic alteration more distal to the veins. Stein (2018), was of the opinion that geological controls, such as alteration, have not been studied in any great detail.
Given the lithological, structural, mineralogical and alteration characteristics observed at the Project and specifically in the Bethania Mine vein system, mineralization identified to date can be classified as volcanic-associated, polymetallic intermediate sulphidation epithermal (“ISE”), with significant accumulations of silver, lead, zinc, copper, and gold.
Dominated by silver, Bethania Mine’s polymetallic mineralization is fairly typical in its composition, containing appreciable amounts of lead, zinc, gold, and copper. On the basis of multi- element assays and production history, it is clear that dominant sulphide minerals include silver sulfosalts (e.g., Ag3AsS3, Ag3SbS3), galena (PbS), sphalerite (ZnS), and chalcopyrite (CuFeS2).
Mineralization of the major veins, Española and 12 de Mayo, can be more than 1.5 meters thick, but averages are about 0.6 meters; minor veins average about 0.3 meters in thickness.