The Iron Crown (Nimpkish Iron) past producer is located on the southwestern side of the Nimpkish River, below Mukwilla Creek and approximately 9.5 kilometres southeast of the river mouth on Nimpkish Lake.

In the area of the Iron Crown occurrence, north striking carbonates and calcareous sediments of the Quatsino and Parson Bay formations overlie Karmutsen Formation tholeiitic basalts, all of the Upper Triassic Vancouver Group. Lower Jurassic Bonanza Group andesitic to rhyodacitic lava, tuff, breccia and minor sediments are coeval with, or genetically related to, granodiorite of the Nimpkish batholith of the Early-Middle Island Plutonic Suite. Strong regional north to northwest trending faults, often defining intrusive and lithological contacts, traverse the area.

The occurrence is at the contact between coarsely crystalline Quatsino Formation limestone and fine-grained massive amygdaloidal andesite exhibiting sericite, calcite and actinolite alteration with amygdules filled with epidote, calcite or actinolite. Pyrite and pyrrhotite are disseminated through the andesite. Laumontite and calcite veins are present.

Leucocratic quartz monzonite and diorite intrude the volcanics and limestone. Contacts with the volcanics are diffuse, and recrystallized andesite cannot readily be distinguished from intrusive rocks. Feldspar porphyry dikes, an aplite dike and a felsite dike are also recognized. The magnetite contact with the limestone is sharp. The andesite is diffuse and evidenced by skarn. The magnetite is relatively pure, but contains up to 50 per cent calcite lenses with chalcopyrite, pyrite and sphalerite. Calcite and sulphides are considered to be post-ore (Geological Survey of Canada Bulletin 172, page 73).

A 55 metre long, 8 to 9 metre wide magnetite exposure occurs along the Nimpkish River. Some 200 metres west of the river, several outcrops of magnetite occur along a ridge and are estimated to represent a lens at least 116 metres long and 18 metres wide. A third magnetite body, indicated by magnetometer surveys only, measures 146 by 18 metres and lies between the river and ridge deposits. These 3 occurrences are believed to represent the 3 fault-separated orebodies of Sangster (Geological Survey of Canada Bulletin 172, page 73). The faults are marked by breccia zones up to 1.5 metres wide, gouge, chlorite, hematite-coated slip surfaces and slickensided magnetite ore and country rock.

Ore samples taken in 1942 assayed 59.6 to 63.9 per cent iron, averaging 62.1 per cent iron (Cameron, 1942). Phosphorous and sulphur contents are reported to be very low. Between 1959 and 1963, 2,175,683 tonnes of ore were mined.

Indicated (probable) reserves at Iron Crown are 1,632,924 tonnes grading 46.2 per cent iron and 1.33 per cent sulphur (Minister of Mines Annual Report 1956). The reserve figures are pre-production; the deposit has been subsequently mined out.

In 2010, sampling of the waste dumps yielded an average of 7 per cent magnetite (Assessment Report 32150). In 2011, sampling of tailings yielded from 16.9 to 25.3 per cent iron and 0.223 to 0.460 per cent copper (Assessment Report 33783). In 2014, three tailings/dump samples yielded from 0.223 to 0.460 per cent copper, 2.4 to 4.2 grams per tonne silver and 16.9 to 25.3 per cent iron (Assessment Report 35179).

Work History

Magnetite was discovered in the area in 1897 and the deposits were first reported on by E. Lindeman in 1910. In 1954, seven diamond drill holes, totalling 405 metres, were completed. In 1955, the Iron Crown (Lot 126) and Rhoda (Lot 919) crown-granted mineral claims were optioned by Nimpkish Iron Mines. Exploration of the iron deposit was continued by surface work and diamond drilling on both lots with six inclined and sixty-two vertical holes being completed, totalling 2115 metres. In 1959 and 1960 the milling plant and dock-loading facilities were constructed with milling commencing in mid-November. In 1961, mining and milling operations continued along with sixteen diamond drill holes, totalling 778.5 metres, were completed on an extension of the ore zone on the south side of the pit. Seven diamond drill holes were completed on a magnetic anomaly, located 300 metres northwest of the pit. In 1962, open pit quarrying continued on the Road, East, South and River pits. Stripping and twenty-one diamond drill holes, totalling 899.4 metres, were continued on the magnetic “A” anomaly. During 2010 through 2012, Homegold Resources prospected and sampled the area as the Nimp, Klac and Klack claims. In 2014, Guohua Furen Mining Inc. completed a minor program of rock and metallurgical sampling on the Nimpkish Iron property.