The Thorn I (I zone) occurrence area is underlain by a Cretaceous biotite-hornblende diorite stock (the Thorn stock) related to the Windy Table Complex. This stock intrudes Carboniferous volcaniclastics of Stikine Assemblage consisting of chloritic tuffs. These rocks are cut by rhyolitic augite-feldspar porphyry dykes of the Sloko Group of Eocene age.

The I zone is comprised of numerous subparallel quartz-pyrite-tennantite veinlets in intensely sericitized and pyritized Cretaceous feldspar-quartz-biotite porphyry. Most veins strike 070 to 100 degrees and dip 40 to 75 degrees to the south; a few strike 200 to 220 degrees and dip 40 to 70 degrees to the northwest. Individual veins range up to 1.5 metres in width; the entire zone would average about 10 per cent veining across a true width greater than 25 metres. To the south, the intensely sericitized and veined I Zone transitions through a few metres of weakly altered porphyry into relatively fresh, non-pyritic porphyry. The northwestern edge of the I Zone exposure is bounded by a fault which juxtaposes it with little-altered Cretaceous andesitic lapilli tuffs. To the east, the strike extent of the I Zone is unknown, since it disappears under heavy vegetation within a few metres of Eye Creek.

In March 2002, First Au Strategies Corp. (Cangold) optioned the Thorn property from Rimfire and conducted two stages of exploration that summer. A drill hole (02-09) yielded 3.16 grams per tonne gold, 100.5 grams per tonne silver and 0.377 per cent copper over 2.30 metres (Baker, D. (2010-10-28): 2010 Technical Report on the Thorn Property).

In 2010, sampling of the I zone yielded up to 9.28 grams per tonne gold, 760 grams per tonne silver and 0.30 per cent copper over 0.7 metre (Sample 206842; Baker, D. (2010-10-28): 2010 Technical Report on the Thorn Property).

In 2011, drillhole THN11-54 tested the I zone beneath the unconformity between Windy Table Suite volcanic rocks and the Thorn Stock. Previous drilling in 2002 intersected veining and faulting in holes THN02-09 and -10; THN02-09 intersected 5.08 grams per tonne gold and 156 grams per tonne silver over 1.04 metres at a depth of approximately 20 metres below surface, but suffered from poor recovery (Assessment Report 27120). THN11-54 passed through the unconformity between Windy Table and Thorn Stock at 55.60 metres, without any change in alteration or mineralization. It cut the I Zone fault between 90.24 and 105.78 metres; the fault hosts scattered pyrite-chalcopyrite-sulphosalt-silica veins. The fault zone averages 1.25 grams per tonne gold and 54 grams per tonne silver across 15.83 metres, including 3.13 grams per tonne gold and 123 grams per tonne silver across 4.85 metres (Assessment Report 32769). The I Zone dips steeply to the southeast and is open to the northeast and southwest; THN11-54 intersected it about 70 metres below surface. It appears that THN11-54 was stopped short of the projected location of the Lagavulin vein (new MINFILE), the trace of which extends about 2 kilometres from the I zone area to the south-southwest.

The I-Zone was interpreted as a zone of complex intersecting faults and veins (on maps supplied by Brixton) (SRK Consulting (Appendix A, Assessment Report 34506) The final structural map interpretation by SRK shows the presence of north-northeast striking fault zones with associated northeast and east-west striking Riedel faults. Drill hole THN-11-54 intersected a fault zone containing sulphides with elevated gold-copper-silver-lead-zinc values. The mineralization is confined to a fault zone that has pervasive sericite and silica alteration. Silicification post-dates at least one earlier phase of brecciation. Pyrite, sphalerite and sulphosalt (presumable enargite and/or tetrahedrite) mineralization occurs in the micro-veins and the matrix of the earlier breccia. Mineralized and silicified early breccia clasts are observed in a later phase of breccia that is cemented by vuggy quartz (Assessment Report 32769, THN-11-54). The fault zone also has slip planes with talc infill and slickenfibres. SRK interprets this I-Zone to be similar to the previously described vein systems, with multiple phases of mineralization and alteration within an active fault system.

See Camp Creek Corridor (104K 116), Oban (104K 168) and Thorn (104K 031) for related geological and historical details of the Thorn Property.