The Thorn A zone area is underlain by feldspar-quartz-biotite-phyric diorite of the Late Cretaceous of the Windy Table Complex (Thorn Stock), which intrudes Upper Triassic Stuhini Group volcanic and sedimentary rocks. A second Late Cretaceous magmatic event deposited subaerial volcanic rocks of the Windy Table Suite nonconformably upon the Thorn Stock, coeval with a second stage of plutonism.

The A Zone comprises an impressive exposure beside Eh Creek immediately south of the Thorn Stock contact. At this location, a 4 metre wide quartz-barite vein, with spotty pyrite and chalcopyrite, cuts across the creek, forming a small waterfall. It follows a fault zone trending 125 degrees and dipping 80 degrees south which separates Stuhini Group andesite to the southwest from well-bedded clastics to the northeast. Flanking the quartz-barite vein to the northeast is a 1.25 metre vein of brecciated massive pyrite with strikingly different metal ratios, raising the possibility that it represents a separate mineralizing pulse emplaced along the same fault structure. The A Zone was discovered by Anaconda, who drilled 250 metres in 8 short holes, testing it with mixed success along 120 metres of strike length to the southeast of Eh Creek. The best A Zone core intersection graded 2.40 per cent copper, 201 grams per tonne silver and 1.4 grams per tonne gold over 2.4 metres (private reports by Adamson (1963-65) for Julian Mining, as reported in Assessment Report 27673).

The A Zone was re-examined in 2004. Sample 276495 returned 1.01 grams per tonne gold and was collected from the same location as the 2000 sample 206844.

In 1981 it was reported that the area known as the Drill Creek zone and A zone consisted of brecciated rhyolite, within a sequence of interbedded rhyolites and andesites, which contained chalcopyrite, pyrite, quartz and minor galena, barite, calcite and siderite. A rock sample assayed over 1.0 per cent copper and 7.2 grams per tonne silver (Assessment Report 10243).

In 2000, chip samples averaged 0.315 gram per tonne gold, 19.2 grams per tonne silver, 0.818 per cent copper over 5.25 metres, including 1.28 grams per tonne gold, 52.8 grams per tonne silver and 0.139 per cent copper over 1.25 metres (Baker, D. (2010-10-28): 2010 Technical Report on the Thorn Property).

The J Zone was reported by Anaconda in Hook Creek on the slope west of La Jaune Creek. Mineralization consists of low grade disseminated chalcopyrite with much pyrite in a well altered intensely sheared porphyry. The trend of this shearing is on strike with the strong fault structure that cuts across the A Zone to southeast and possibly may be its extension.

Work History

From about 1963 to 1965, the Thorn property area was worked by Julian Mining, which included geophysical, geochemical and drilling programs. In 1965 the zone was geophysically surveyed (IP and tested by drilling four X-ray holes (179 metres; mineralized outcrops were initially sampled in 1963 by drilling four Pack Sack drill holes (79 metres) (Assessment Report 15897). In 1981 Woodcock and two geologists spent one day collecting specimens and rock chip samples. The specimens have been examined with a petrographic microscope for alteration and rock types (Assessment Report 10243). In 1986, Inland Recovery Group Ltd with American Reserve Mining Corp reported on the A zone as the Drill Creek zone but no work is reported. In 2000, Rimfire examined and sampled the A zone. The A Zone was re-examined in 2004 by Cangold Limited and Rimfire. Sample 276495 assayed 1.01 grams per tonne gold and was collected from the same location as the 2000 sample 206844.

In 2020, Brixton Metals Corporation completed a program of geochemical (rock and soil) sampling, a 12.5 line-kilometre ground induced polarization survey, a 715 line-kilometre airborne magnetic and electromagnetic survey and 19 diamond drill holes, totalling 5292 metres, on the area of as part of the Thorn property. Drilling was performed on the Outlaw (MINFILE 104K 176) occurrence area.

Refer to Thorn (MINFILE 104K 031) for details of the work history of the Thorn property, of which the A zone is part of.