The Jessie mine is on the southeast coast of Moresby Island. It is situated on the ridge between Harriet Harbour and Ikeda Cove about 2.4 kilometres southeast to the entrance to the Harbour at an elevation of 152 metres.
The Jessie is the key claim of a large group of claims acquired by The Granby Mining Company Limited, and its subsidiary, Jedway Iron Ore Limited. Jedway acquired 61 recorded claims, three mineral leases and ten Crown-granted claims. The three mineral leases cover four reverted Crown-grants as follows: Mineral Lease 2, Adonis (Lot 1865) (103B 027); Mineral Lease 37, Hot Punch (Lot 1976), and Iron Duke (Lot 1977); and Mineral Lease 105, Jessie (Lot 1861). The ten Crown-granted claims were as follows: Moresby Island (Lot 78) (103B 036); Magnet (Lot 79)(103B 034); Blue Belle (Lot 80) (103B 033); Ajax (Lot 81); Sandwich Fraction (Lot 92); Emma (Lot 854); Delia (Lot 2597); Lizzie B (Lot 2604); Cypress Queen (Lot 2607); Mattie H. Fraction (Lot 2608). These Crown-granted claims were originally part of the large block, owned by J.S. McMillan (see Copper Queen, 103B 035). In addition, Granby holds 64 recorded claims in the vicinity.
The Jessie showings were located around 1908 by the Trethawey Brothers and "a considerable amount of work" was reported done on them. In 1912, the Jessie was Crown-granted to P. Drummond, the Hot Punch and the Iron Duke to R.R. Hill and the Harriet, Lot 86, to R.A. and J.0. Trethawey. These covered 116-35 acres. These showings are not rich in chalcopyrite so interest in the properties lapsed.
Little attention was paid to the properties until 1956 when Dr. J.M. Black, for Western Canada Steel Limited, explored the area and conducted a magnetometer survey over the showings. In 1959 Silver Standard Mines Limited acquired an option on the Jessie claim from Consolidated Exploration Company Limited, the Limestone, Diorite and Chance fraction claims from Western Canada Steel Limited, and the Hot Punch and Iron Duke from J.M. Black. A diamond drilling program was started and by 1960, 53 holes totalling 4988 metres had been drilled on the Jessie and Limestone claims, 22 holes totalling 467 metres on the Magnet, 3 holes totalling 329 metres on the Adonis and 7 holes totalling 169 metres on the Blue Belle. This outlined 226,796 tonnes.
In January 1961, The Granby Mining Company Limited optioned, and after additional drilling purchased, the property and formed Jedway Iron Ore Limited in April of that year. With further drilling the reserves were estimated to be 4,263,769 tonnes which would produce 2,331,465 tonnes of concentrate. The company had a contract with Sumitumo Shoji Kaisha of Japan to supply 1,814,370 tonnes of concentrate grading 62 per cent iron over a period of five years. Production by open-pit methods started in late summer 1962, and the 1,996 tonnes per day mill was put into operation in September. In 1964 some ore was contributed by the nearby Adonis property (103B 027) and in 1966 by the Rose property (103B 029).
During 1962 and 1963 an adit was driven 465 metres under the open pit at the 145 metre elevation. From this adit 4542 metres of diamond drilling proved reserves of 2,494,759 tonnes of 35 per cent iron between the adit level and the proposed bottom of the open pit at 229 metres elevation. Underground mining started in 1966.
Recoverable reserves on January 1, 1966, were 334,842 tonnes in the pit and 516,641 tonnes in one underground stope, for a total of 851,484 tonnes grading 35 per cent magnetic iron. An additional 873,437 tonnes of the same grade exists underground but was judged to be uneconomic. The ore bodies were exhausted and the mine closed in February, 1968.
In 1972, trenching, totalling 3737 cubic metres, was done on the Limestone and Jessie claims by Jedway Iron Ore Limited.
The Vancouver Group, Upper Triassic Karmutsen Formation, consisting of altered basalts is overlain by the lower part of the Jurassic to Triassic Kunga Group consisting of limestones and argillites. The strata generally strike east with an average dip of 050 degrees north. These rocks are cut by a sequence of intrusive bodies, from oldest to youngest, as follows: greenstones; diorite porphyry; diorite to quartz diorite of the Jedway Stock; rhyolite dikes; and small andesitic to basaltic dikes. Skarnification and mineralization occurred after intrusion of the Jedway Stock, which is part of the Middle to Late Jurassic Burnaby Island Plutonic Suite.
The Jessie orebodies are on the northern flank of a west northwest trending domal anticline near its intersection of a 140 degree trending fold and fault structure of probable younger age. The ore lenses are primarily in the Karmutsen greenstones, conformable with bedding, adjacent to and above the contact with the Jedway Stock. Two major fault orientations are the larger north trending, 45 to 75 degree dipping faults and the smaller 60 to 80 degree, similar dipping faults, which are sometimes offset by the north faults.
The mineralized bodies occur as replacement bands of magnetite separated by skarn, chloritic greenstone or diorite porphyry. In general, there are three bands: the upper, 30 to 35 metres below the Kunga contact and about 6 metres thick; the main or intermediate, 6 to 12 metres below and 12 to 24 metres thick; and a lower, 24 to 30 metres below the main and about 7 metres thick. These bands maintain their character over 250 metres of dip and strike length then coalesce at the upper elevations near the basin-like mass of diorite porphyry and limestone. As the bands reach a major fault zone, they follow up the faults and resemble dikes. These enlarge downward and then diverge into the bedding attitudes.
During the development of the Jedway Iron Mine, ore assayed 49 per cent iron, 0.025 per cent copper, 0.78 per cent sulphur, 0.09 per cent titanium and 0.035 per cent phosphorous (Minister of Mines Annual Report 1959, page 14). During production the concentrate averaged 62 per cent iron (Bulletin 54, page 199).
The total drill indicated ore reserves in 1961 were 4,260,000 tonnes of magnetite ore (Minister of Mines Annual Report 1961, page 15). The mine operated continuously from 1962 to 1968 when the ore was mined out. The mine used both open pit and underground methods simultaneously to mine the Jessie zone. During the period of production 3,938,702 tonnes of ore was milled producing about 2.1 megatonnes of iron concentrate. Production includes ore from the Adonis (103B 027) in 1964 and ore from the Rose (103B 029) in 1966.