The Myra Falls Operation includes the Lynx (092F 071), Myra (092F 072), Price (092F 073) and H-W (092F 330) deposits and associated zones. The Myra (Paramount) volcanogenic massive sulphide deposit occurs within the southern part of the Buttle Lake uplift. This discrete belt of northwest striking Upper Paleozoic rocks is bounded on the east by Upper Triassic Karmutsen Formation volcanics (Vancouver Group) and on the west by the Early to Middle Jurassic Island Plutonic Suite. The geology of the uplift has recently been reinterpreted and the stratigraphy has been reassigned to several new formations of a redefined Sicker Group and the new Buttle Lake Group (formerly the upper part of the Sicker Group) (Juras, 1987; Massey, Personal Communication, 1990).

The Buttle Lake Group consists of: (1) the Lower Permian(?) Henshaw Formation composed of conglomerate, epiclastic deposits and vitric tuffs; and (2) the Lower Permian to Pennsylvanian Azure Lake Formation (formerly Buttle Lake Formation) consisting of crinoidal limestone and minor chert.

The Sicker Group consists of: (1) the Mississippian(?) or Pennsylvanian(?) Flower Ridge Formation largely comprising coarse mafic pyroclastic deposits; (2) the Lower Mississippian(?) Thelwood Formation, a bedded sequence of siliceous tuffaceous sediments, subaqueous pyroclastic deposits and mafic sills; (3) the Upper Devonian Myra Formation consisting of basaltic to rhyolitic flows and volcaniclastic rocks, lesser epiclastic sediments, argillites and cherts, and massive sulphide mineralization; and (4) the Upper Devonian or older Price Formation comprising feldspar-pyroxene porphyritic andesite flows, flow breccias and minor pyroclastic deposits.

The Buttle Lake uplift stratigraphy indicates deposition in a rift basin in an island arc environment. It has been intruded by granitic dykes related mainly to the Island Plutonic Suite. A 1 kilometre wide stock of Tertiary intrusives lies about 1.5 kilometres north-northeast of the deposit. This stock (formerly called Catface Intrusions) is probably related to the Mount Washington Intrusive Suite of Late Eocene to Early Oligocene age (Nick Massey, Personal Communication, May 1990).

The major occurrences in the Buttle Lake area lie along a northwest striking, 65 degree southwest to steeply northeast dipping zone that is approximately 6 kilometres long. The rocks have been metamorphosed to the lower greenschist facies, and have been deformed along northwest trending subhorizontal open folds. Several regional west-northwest to north trending faults occur with maximum lateral displacements of 850 metres. The faults are considered to be post- Mesozoic, and are probably related to Late Cretaceous uplift. The contact between the Myra Formation and the overlying Thelwood Formation is marked by a 2 to 40 metre wide zone of strong schistosity that may represent an Upper Paleozoic low angle fault.

The Myra Formation, dated at 370 million years (Juras, 1987, page 109) contains all of the massive sulphide horizons of the camp. The Myra, Lynx (092F 071) and Price (092F 073) deposits lie at the same stratigraphic level (the "Mine Sequence" of Juras). The H-W deposit (092F 330) lies below them at the base of the Myra Formation. Westmin Resources' Myra Falls Operations has developed these deposits as four mines. In 1990, the Lynx and H-W mines fed a 4000-tonne per day mill; the Myra mine is depleted and the Price deposit has yet to be used as a source of mill feed.

The massive sulphide horizon lies within a zone of quartz- feldspar rhyolite tuff and minor chert. The tuff is underlain by dacite flow breccia and tuff, breccia that includes clasts of H-W mineralization, andesite flows, the rhyolitic H-W horizon, and the Price Formation. Rocks in the feeder zone below the massive sulphide horizon have undergone sericitization and silicification. Pyrite alteration is evident from disseminated pyrite and pyrite stringer zones.

Overlying the massive sulphide horizon are pillow basalts, mixed pyroclastics and tuffs, felsic rhyolite and flow breccia, all of which are overlain by the Thelwood Formation.

The lenses of massive sulphides occur in a gangue of quartz, sericite, chlorite and talc, and comprise chalcopyrite, galena, sphalerite, pyrite and pockets of barite. Minor tennantite, bornite, tetrahedrite, pyrrhotite, digenite, covellite and stromeyerite are present.

The Myra mine started production in 1972. Pre-production reserves in 1972 were 478,000 tonnes averaging 3.43 grams per tonne gold, 198.88 grams per tonne silver, 0.9 per cent copper, 1.7 per cent lead and 8.8 per cent zinc. These reserves included a high- grade zone of 95,072 tonnes containing 7.89 grams per tonne gold, 812.67 grams per tonne silver, 1.2 per cent copper, 1.3 per cent lead and 8.1 per cent zinc. Mineable reserves were depleted in 1985.

According to Westmin Resources Annual Report for 1988, by the end of its life, the Myra mine had contributed 11.4 per cent, or 1,045,450 tonnes, of a January 1, 1989 total of 9,170,609 tonnes milled at the Myra Falls Operations. The overall grade of the total ore milled was 2.16 grams per tonne gold, 81.0 grams per tonne silver, 1.83 per cent copper, 0.78 per cent lead and 6.58 per cent zinc (Westmin Resources Limited Annual Report for 1988, page 8). Production data is included with Lynx (092F 071).

Production statistics of the Myra mine have been combined with those of the Lynx and H-W mines. Reported production for the Myra mine from 1972 to 1985 (combined with the Lynx (092F 071) and including the H-W (092F 330) is 2,287,937 tonnes mined. To the end of 1988; the combined milled production of the Myra Falls Operations totalled 9,162,835 tonnes containing 15,205,759 grams of gold, 615,419,293 grams of silver, 153,750 tonnes of copper, 56,670 tonnes of lead, 525,606 tonnes of zinc and 1,348 tonnes of cadmium.