The Churchill magnetite occurrence is located at an elevation of approximately 1150 metres on a ridge separating Lime and Fault creeks to the southeast and the eastern headwaters of the Kaouk River to the northeast.
Regionally, the area lies within a broad northwest-trending sequence of interbedded sediments and volcanics of the Upper Triassic to Lower Jurassic Parson Bay Formation (Bonanza Group) and Upper Triassic Quatsino Formation (Vancouver Group). This assemblage lies on the northeastern flank of the extensive granodiorite Zeballos intrusion phase of the Jurassic Island Plutonic Suite.
The area lies within a belt of mineralization comprising nine or more similar occurrences that extend from the Zeballos River for approximately 10 kilometres in a north-northwest direction. The mineralization occurs at or near the conformable contact between the Upper Triassic Vancouver Group—comprising Quatsino Formation crystalline limestone and overlying highly altered and folded Parson Bay Formation volcanic and sedimentary rocks—and the Lower Jurassic Bonanza Group.
Locally, the mineralization lies along the contact between diorite of the Jurassic Island Plutonic Suite and Upper Triassic Quatsino Formation (Vancouver Group) limestone. The limestone strikes 330 degrees and dips 45 degrees north and is cut by diabase dikes ranging up to 10 metres in width. Granodiorite dikes up to 30 metres wide occur in the main diorite intrusions and have locally fractured or brecciated the hostrock. Several narrow felsic dikes cut both diorite and granodiorite. Faulting includes the north-northwest–trending Hiller fault and a set of north- to northeast-trending faults.
The mineralization comprises massive magnetite with disseminated pyrite and pyrrhotite, and patchy limonite, occurs as irregular lens-shaped bodies at the northeast-trending contact, replacing limestone. Small lenses of unaltered limestone remain within the magnetite. The main magnetite body measures 76 by 76 by 16 metres. A small patch of garnet-epidote skarn is present at the southwest corner of this body. Much smaller streaks and pods of magnetite occur over an area of 200 metres from the main occurrence.
In 1951, drilling yielded an estimated tonnage of 711 233 tonnes of magnetite grading 55.69 per cent iron, 1.8 per cent sulphur and 0.25 per cent copper (Assessment Report 433).
In 1967, reserves of 726 000 tonnes were quoted (Property File - R.N. Saukko (1967-03-15): Report on Hiller-Churchill Properties 1966); assays on purest material returned values of 67.34 per cent iron, 0.053 per cent sulphur and 0.026 per cent phosphorus (Geological Survey of Canada Memoir 272, page 69), but Saukko estimated the average grade at 35 to 40 per cent (Property File - R.N. Saukko (1967-03-15): Report on Hiller-Churchill Properties 1966).
In 1988, ore reserves of approximately 907 000 tonnes averaging 30 to 40 per cent iron were reported for the Churchill zone (Property File - Footwall Explorations Ltd. (1989-01-12): News Clippings - Hiller-Churchill Property).
In 2010, a sample (781162) assayed 25.59 per cent iron (Assessment Report 31911).
Other zones of magnetite mineralization are reported in the headwaters of Fault Creek, approximately 350 metres northwest and 600 metres north of the main zone on the Churchill 3 and 5 claims, respectively. Three samples from the northwestern zone on the Churchill 3 claim yielded from 58.88 to 66.40 per cent iron, whereas four samples from the northern zone on the Churchill 5 claim yielded from 49.48 to 68.92 per cent iron (Property File - unknown [unknown]: Assay Plan Map of the Magnetite Deposits on the Churchill Mineral Claims).
Work History
In 1951 and 1952, the Argonaut Mine Division of Utah Mining and Construction Ltd. completed 20 diamond drill holes, totalling approximately 600 metres, on the Churchill claims. In 1956, the area immediately northwest was staked as the Artlish group by Mr. Skogland. In 1961, BHP-Utah Mines optioned the Artlish group claims and completed a program of geological mapping and ground and airborne geophysical surveys on the area. In 1962, Falconbridge Nickel Mines completed approximately 300 metres of drilling on the Churchill property. In 1966, a further 307.2 metres of drilling was completed on the Churchill area.
In 1985, Falconbridge Ltd. completed a program of geological mapping, trenching, ground magnetic surveys and diamond drilling on the Churchill 2 and Hiller 25-26. In 1986, Falconbridge Ltd. completed an airborne geophysical survey on the Hiller and surrounding Zeb claims. In 1988, Footwall Explorations Ltd. completed 900 metres of drilling on the Hiller-Churchill property. In 2010, Selkirk Metals Corp. prospected and sampled the area.