Location and Claims
The Corona property consists of six claims totaling 850 hectares in the extreme southwest part of the Uruachic camp, a few kilometers west of the town of Gosagachic. It is subject to the option agreement with Fresnillo PLC.
Under the terms of an earlier agreement Comstock Metals earned a 60% interest in the Corona property from Golden Goliath. Subsequently Comstock was unable to meet its funding requirements and they were diluted to 50%. Golden Goliath’s Option Agreement with Fresnillo includes the Corona property and Golden Goliath will pay to Comstock its portion of the option payments (50% of 1/7 , as there are 7 properties in the agreement).
The Corona property is underlain by intensely altered volcanic rocks of the favourable Lower Volcanic Sequence that are cut by brecciated and altered intrusive rocks and overlain by a relatively thin section of the Upper Volcanic Sequence rhyolitic tuffs. Visible gold can be panned from the soil on a hilltop just south of the Northeast Zone, as well as from the Esperanza claim.
The Esperanza Showing is exposed in an old adit dug into an overburden covered hillside, mineralization consists of a coarsely banded quartz vein that is up to 30 cm wide hosted within sericite-altered and silicified diorite. Zinc and lead minerals are evident as sphalerite and galena. Grab samples taken in 2002 and 2007 from the adit returned assays of 12.43 g/t Au, 2,634 g/t Ag, 8.35% Pb, 3.84% Cu and 3.84% Zn (Golden Goliath Resources) and up to 42.6 g/t Au and 76.4g/t Ag across 15 cm from in-house sampling.
The Esperanza showing itself may be part of a larger east-west trending set of structures that returned high gold and silver values in earlier programmes. Approximately 1000 metres west is the Cerro el Cruz prospect, reportedly of similar mineral-style, and 200 to 300 metres to the east highly anomalous rock and soil samples have been collected, some returning gold values exceeding 14,000 ppb.
The Esperanza Zone is similar target to the Santo Nino Vein (Fresnillo) where 1st drill hole at 300 m depth drilled 1.6 g/t Au, 1087 g/t Ag, 0.4% Pb, 0.7% Zn/3 m. Santo Nino Vein dimensions are 2.5 km long x 500 m deep x 2 m wide.
A New Example of High Sulphidation Epithermal Gold Mineralization in Northern Mexico
Recent core drilling and geological mapping has shown that the gold-silver mineralization at Corona is also “High Sulphidation Epithermal” in origin. At Corona prospecting and mapping has found an area known as the “Jerry Zone” where the rhyolite flows and tuffs of the Upper Group are highly fractured, brecciated and altered to an alunite-rich rock that passes into outcrops of leached rhyolite with extensive and well-developed vuggy and residual silica. Between the areas of near-massive vuggy quartz the host rock is highly fractured and has spectacular networks of dark vuggy silica veinlets and silica-cemented hydrothermal breccia The zone of vuggy silica has been traced in outcrop and float over a distance of 800 metres. At the northern end of the zone extensive areas of alunite alteration occur within pumice and tuff that is in fault-contact with the Jerry Zone. The mineralogy, occurrence and trace element geochemistry suggests that the Jerry Zone is the high-level “lithocap” of a concealed mineral system.
Drilling during February and March 2012 started on the “Northeast Zone”, 250 to 300 metres east of Jerry. Here mineralization is focused along the contact between the Upper and Lower Volcanic Groups as zones of advanced argillic alteration marked by pyrophyllite, sericite and hematite. Similar mineralization is present in the NE Extension, up to 500 metres to the southeast. This mineralization is also part of a high sulphidation system. Comstock’s 2012 drilling started testing a portion of the area between the NE Extension and the southern end of Jerry with some relatively shallow drill holes (CO12 – 64 to 67), resulting in the discovery of extensive thicknesses of highly fractured granodiorite, diorite, and hydrothermal breccia that is densely fractured and often well-mineralized. This “porphyry-style” gold mineralization is oxidized, with pervasive hematite, and silicification plus “clay” alteration that is locally intense, but pyrite is rare or absent.
It appears that drilling beneath the lithocap and extending into un-drilled terrain north and south may define an intrusive body forms a “cupola” or dome of highly fractured and brecciated porphyry that may extend well beyond the areas of both current and historic drilling.