The Firesteel (Calcine) occurrence is located at an elevation of approximately 1260 metres on the ridge of a small set of hills west of the Finlay River and approximately 2.1 kilometres northwest of the northern end of Thutade Lake. The occurrence lies on the eastern edge of the Spatsizi Plateau at the southern end of the Toodoggone Gold Camp, about 202 kilometres north-northwest of the community of Germansen Landing .

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. Devonian to 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, pyroclastic rocks and marine sedimentary rocks. The Asitka and Stuhini groups rocks have been intruded by the Early Jurassic granodiorite to quartz monzonite Black Lake Suite and are in turn unconformably overlain by or faulted against Lower Jurassic calc-alkaline volcanics of the Toodoggone Formation (Hazelton Group). To the west these units are overlain by sedimentary rocks of the Middle to Upper Cretaceous Sustut Group.

The dominant structures in the area are steeply dipping faults that define a prominent regional northwest structural fabric trending 140 to 170 degrees. 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, the showing area is underlain by pale grey, massive, recrystallized fossiliferous limestone of the Asitka Group and mafic volcanics of the Stuhini Group. The mafic volcanics comprise dark green mafic tuffs, lapilli tuffs and plagioclase porphyry flows. Greywacke, chert and volcaniclastic conglomerate are associated with the volcanics. Mineralization consists of a breccia replacement-type mineralization developed at or near the volcanic-limestone contact. Limestone in the area contains minor amounts of galena, sphalerite, chalcopyrite and pyrite.

The main zone of mineralization consists of massive sphalerite, chalcopyrite and galena clasts or nodules in a sphalerite-carbonate matrix (smithsonite) forming an apparently circular deposit of cemented breccia. The mineralized zone is estimated to be 45.7 metres in diameter by 4.5 metres thick. The ‘pancake’-shaped mineralized breccia zone is hosted in a limestone that strikes approximately 135 degrees and dips shallowly (10 to 25 degrees) to the southwest. To the east and north, barren andesitic volcanics have been identified in fault contact with the limestone. To the south and west, trenching has identified additional replacement-style beds and lenses and float boulders of massive sphalerite, galena, pyrite and chalcopyrite with widths up to 2.1 metres.

A second zone of ‘low-grade’ replacement lead-zinc mineralization, exposed by Cominco Ltd. in the former trenches no. 56 and 57, is located approximately 130 metres to the southeast of the main zone. The mineralized zone comprises pyrite, sphalerite and minor galena in a 2.1-metre-wide brecciated and silicified zone at the contact of limestone and a tuff that dips 25 degrees to the southwest.

A third zone of mineralization, located approximately 150 metres west of the main zone, is exposed by trenching in an area of mineralized float. Mineralization comprises a 22.5-centimetre-wide zone of massive galena with minor sphalerite, pyrite and chalcopyrite as a steep zone in limestone.

Approximately 300 metres further to the southwest, an open cut (no. 101) exposes a 0.6- to 0.9-metre-wide, north-trending vein or replacement zone of nearly massive pyrite, sphalerite and minor tetrahedrite in limestone over a strike length of 3.6 metres.

Another zone of mineralization, consisting of erratic freibergite-bearing quartz veins, occurs to the south of the main zone.

In 1933, sampling of the main zone is reported to have yielded up to 11.5 per cent zinc, 0.50 per cent copper and 54.0 grams per tonne silver over 4.8 metres (sample 14152; Assessment Report 25003).

In 1947, sampling of the southeastern zone, exposed in trench no. 57, is reported to have yielded up to 2.3 per cent zinc, 0.3 per cent lead and 106.0 grams per tonne silver over 2.1 metres, whereas sampling of the southwestern zone, exposed in trench no. 101, yielded 0.80 per cent zinc, 1.2 per cent copper and 177.8 grams per tonne silver over 0.9 metre (Assessment Report 25003).

In 1972, the main zone was reported to contain an estimated 27,215.5 tonnes grading 5 per cent zinc, whereas a grab sample assayed 0.20 per cent lead, 8.35 per cent zinc and 26.3 grams per tonne silver (Assessment Report 4200).

In 1980, the main zone was determined to grade approximately 34.29 grams per tonne silver, 0.30 per cent copper and 10 per cent zinc, whereas samples of the freibergite-bearing quartz veins are reported to have yielded up to 11,163 grams per tonne silver over 0.46 metre and 1134 grams per tonne silver over 1.2 metres (Assessment Report 13531).

In 1996, four samples (11603 to 11606) from the main zone yielded from 12 to 44 per cent zinc, 0.25 to 0.74 per cent copper and 2.7 to 195 grams per tonne silver, whereas a chip sample (96T107) yielded 10.5 per cent zinc over 1 metre (Assessment Report 25003).

The area was first staked in 1931 by Cominco Ltd. as the Calcine claims, and over the next two years a number of trenches and shafts were developed to locate the source of lead-zinc mineralized float in the area. During 1944 through 1946, Cominco Ltd. completed further programs of prospecting, geological mapping and trenching on the Calcine claims.

In 1957, Granby optioned and examined the property.

In 1961, Newconex conducted a program of geological mapping and a spontaneous polarization survey on the Calcine claims. The following year, Norpex Ltd. completed an electromagnetic survey and three drillholes on the Calcine property.

In 1972, El Paso Mining and Milling Co. completed a program of geological mapping, soil sampling, a 10.5 line kilometre gravity survey and 23.5 line kilometre electromagnetic (VLF) survey on the area as the Firesteel property.

In 1980, Serem Ltd. completed a program of soil sampling on the area. In 1985, a 6.6 line kilometre ground electromagnetic (VLF) survey was completed.

In 1996, Wheathills Resources Inc. completed a program of prospecting, rock sampling and trenching on the area.