The area of the Alunite Ridge occurrence is located at an elevation of approximately 1800 metres on a north-northeast–trending ridge, approximately 3.5 kilometres southwest of the junction of the Toodoggone River with Bronlund Creek.

Regionally, the area is situated within a Mesozoic volcanic arc assemblage, which lies along the eastern margin of the Intermontane Belt, a northwest-trending belt of Paleozoic to Paleogene sediments, volcanics and intrusions bounded to the east by the Omineca Belt and to the west and southwest by the Sustut and Bowser basins.

Permian Asitka Group crystalline limestones are the oldest rocks exposed in the region. They are commonly in thrust contact with Upper Triassic Stuhini Group andesite flows and pyroclastic rocks, and marine sedimentary and volcanic rocks of the Lower to Middle Jurassic Hazelton Group. These rocks have been intruded by plutons and other bodies of the mainly granodiorite to quartz monzonite Early Jurassic Black Lake Suite and are in turn unconformably overlain by or faulted against Lower Jurassic calc-alkaline volcanics of the Toodoggone Formation (Hazelton Group).

The dominant structures in the area are steeply dipping faults that define a prominent regional northwest structural fabric trending 140 to 170 degrees. In turn, high-angle, northeast-striking faults (approximately 060 degrees) appear to truncate and displace northwest-striking faults. Collectively these faults form a boundary for variably rotated and tilted blocks underlain by monoclinal strata.

Locally at the Alunite Ridge occurrence, a 2- to 10-metre thick and 500-metre long high-sulphidation–style alteration zone consisting of intense alunite-silica-illite replacement and localized silica-barite concentrations occurs in porphyritic andesite of the Lower to Middle Jurassic Hazelton Group. The Alunite Ridge alteration and mineralization assemblage is reported to overly and pre-date the nearby low-sulphidation Quartz Lake (MINFILE 094E 301) veins.

In 2003, a grab sample (132666) from the area yielded 6.2 grams per tonne gold, 1080.0 grams per tonne silver, 0.100 per cent copper, 1.00 per cent lead and 3.794 per cent zinc (Assessment Report 27429).

In 2004, a sample (165857) assayed 4.41 grams per tonne gold and 42.7 grams per tonne silver, whereas drillholes testing the west end of the Alunite Ridge zone assayed up to 27.1 grams per tonne silver over 7.5 metres, including 81.8 grams per tonne silver with 0.13 gram per tonne gold over 1.5 metres in drillhole SG-04-16A (Assessment Report 27790).

In 2008, grab samples were reported to have assayed up to 0.98 grams per tonne gold from the silica-barite replacement (Assessment Report 30339).

The BS Gold occurrence is located 400 metres northeast of the Alunite Ridge occurrence and is possibly part of the same shallowly dipping system. The BS Gold showing was identified by a soil geochemical anomaly defined by a 550-metre long section of a soil line with samples at 50-metre spacing. Soil samples yielded an average of 300 parts per billion gold, with individual samples ranging up to 1038 parts per billion gold (Assessment Report 30339). The volcanic rocks in the area are soft, deeply weathered and argillically altered, and are part of the central high-sulphidation alteration zone. At the base of the alunite layer, semi-oxidized tetrahedrite and possible energite have been identified.

In 2005, rocks samples yielded up to 1.6 grams per tonne gold, 847 grams per tonne silver and greater than 1.00 per cent antimony (Assessment Report 28038).

In 2006, a rock sample (G-06322) assayed 0.83 gram per tonne gold, 3.7 grams per tonne silver and 0.177 per cent lead from a kaolinized high-sulphidation–suite rock with no visible sulphides (Assessment Report 28647).

Work History

In 1999, Stealth Minerals staked the initial claims in the area of what is now known as the Sickle-Sofia property and, later that year, Standard Metals conducted a small-scale geochemical program on the area on behalf of Stealth Minerals.

In 2003, Stealth minerals completed a program of rock, silt and soil sampling and 78.4 line-kilometres of ground geophysical surveys on the Pine property. Also at this time, as part of a private-public partnership with the Geological Survey of Canada and the British Columbia Department of Mines and Energy, the Sickle-Sofia property was included in a multi-parameter helicopter-borne geophysical survey over the Toodoggone district. Several high potassium anomalies and low thorium-potassium ratio anomalies were detected.

In 2004, Stealth Minerals expanded the Sickle Sofia property package by staking additional claims. A grid-based soil survey was conducted over 27 square kilometres and a total of 728 rock and 2103 soil samples were collected. The Allunite Ridge high-sulphidation alteration and mineralization was detected in the 2004 soil survey as a soil sample that yielded 771 ppb gold (Assessment Report 27790). Later that year, four diamond drill holes, totalling 622.2 metres, were completed on the occurrence.

Also at this time, Stealth Minerals completed 3323 metres of diamond drilling in 24 holes, designed primarily to test downdip and along strike of the Quartz Lake (MINFILE 094E 301) A to C veins and test the along-strike projection of the Griz-Sickle (MINFILE 094E 237) vein set. The Quartz Peak–Alunite Ridge fence of drillholes (SG-04-15 to SG-04-19) intersected up to 200 metres of chalcedonic quartz breccia, which was weakly mineralized.

In 2005, a program of geological mapping and a 21 line-kilometre induced polarization and ground magnetic geophysical survey was completed. The BS Gold showing was identified by a soil geochemical anomaly.

In 2006, a total of 28 rock samples were taken from outcrop and float. Geophysical surveys were completed in the area between and covering the Sofia (MINFILE 094E 238) to Quartz Lake (MINFILE 094E 301) occurrences.

In 2015, a program of geophysical review completed for Cazador Resources Ltd. on the Sofia property identified five target areas.

In 2017, Cazador Resources completed 239.0 line-kilometres of airborne magnetic surveying and a 2.5 line-kilometre ground induced polarization survey on the Sofia property.

See Sickle Creek (MINFILE 094E 237) occurrence for further details of the Stealth Minerals Limited Sickle-Sophia property.