The Highland Lass (Lot 2341) past producer is located 1.25 kilometres northwest of the summit of Mount Wallace and 2.37 kilometres east of Beaverdell, British Columbia (Assessment Report 15704). The Highland Lass claim is part of the Highland-Bell (Beaverdell) mine (082ESW030) which has mined what is commonly referred to as the 'Highland or Upper Lass' vein system. Initial prospecting began in the Beaverdell area in the late 1880s. The first ore was shipped in 1896. The major producing mines in the Beaverdell silver-lead-zinc vein camp, from west to east, were the Wellington (082ESW072), Sally and Rob Roy (082ESW073), Beaver (082ESW040) and Bell (082ESW030), with numerous other small workings throughout the area. Production commenced on the Highland Lass in 1922. In 1930, R.B. Staples and associates obtained control of the Bell and Highland Lass, however, production was recorded separately until the purchase was complete in 1936. Production continued under the amalgamated Highland-Bell mine owned by Highland-Bell Ltd. Highland-Bell Ltd. was purchased by Leitch Gold Mines Ltd. in 1946 but operations continued as the Highland-Bell mine. In 1953, a down-faulted section of the Lass vein system was found 229 metres vertically lower and developed by a 1600-metre adit. Teck Corp. assumed control of the mine in 1970. In 1986 and 1987, property exploration by Teck Corp. located an eastward ore extension with increased gold content on the lower (2900) level. This included an ore block containing 5442 tonnes grading 1371 grams per tonne silver (Assessment Report 15790). Production ceased in 1991.

Granodiorite of the Westkettle batholith underlies most of the area. It has been intruded by small quartz monzonite porphyry stocks including the Beaverdell, Tuzo Creek, Eugene Creek and Carmi stocks. Other granitic porphyry stocks that intrude the Westkettle batholith are the Beaverdell porphyry. These have been dated by potassium- argon methods as Eocene (Watson, P.H. (1981): Genesis and zoning of silver-gold veins in the Beaverdell area, south-central British Columbia; Leary, G.M. (1970): Petrology and structure of the Tuzo Creek molybdenite prospect near Penticton, British Columbia and Exploration in British Columbia 1995, pages 124-126. The Westkettle batholith has been correlated with the Nelson intrusions that has been dated by potassium-argon and uranium-lead methods as Middle Jurassic. The Westkettle batholith contains remnants of pendants and/or screens of metamorphosed Wallace Formation. The Wallace Formation is believed to be correlative with the upper sections of the Carboniferous to Permian Anarchist Group. Lithologies include metamorphosed andesitic tuffs and lavas, hornblende diorite porphyries, olivine gabbro and hornblendite, hornfels and minor limestone. The contact between the Wallace Formation and the Westkettle batholith is sinuous, trending north with gentle east dips. These are unconformably overlain by Oligocene tuffs and conglomerates and Miocene plateau basalts. Westkettle granodiorite or Beaverdell quartz monzonite are the dominant hostrocks. Mineralization rarely extends into the Wallace Formation to the east.

A series of dikes, ranging in composition from quartz latite and quartz monzonite porphyries to hornblende andesite porphyries, are found throughout the area. In the Beaverdell camp, fine grained, brown andesite dikes, referred to as Wellington-type dikes, are believed to be pre-mineralization. One of these was dated by potassium-argon methods at 61.6 +/- 2.2 Ma (Watson, P.H., 1981). Quartz latite dikes are referred to as Idaho-type dikes and thought to be syn or post-mineralization. One of these has given a potassium-argon age of 50.6 +/- 1.5 Ma (Watson, P.H., 1981).

Beaverdell silver-rich veins are found in a 3.0 by 0.8 kilometre belt, referred to as the Beaverdell silver-lead-zinc vein camp. Five distinctly separate quartz vein systems are arranged roughly en echelon in this structural zone. The west-half contains the Wellington (Lot 2621), Sally (082ESW075, Lot 2092) and Rob Roy (Lot 2093, also part of Sally) systems which all strike east and dip from 70 degrees south to vertical. The Wellington and Sally each comprise two separate veins and the Rob Roy three. In the central part of the zone, the Bell (082ESW030, Lot 2343) comprises two veins which strike east to northeast and dip south to southeast. The eastern part of the zone contains the upper and lower sections of the Lass (082ESW133) and Highland Lass (Lot 2341, also part of the Bell) vein which strikes northeast and dips 50 degrees southeast. In general, quartz breccia veins and stockworks are so complex that continuous mineralized sections are a maximum of a few metres before being faulted or disrupted. Nevertheless, some mineralized zones have been found that extend up to 150 metres horizontally. Faults have been classified into five types based on their orientation, with each type having common orientation, kind of movement and age relationship: (1) high angle, north-striking normal faults, (2) low angle, north trending, strike-slip faults, (3) northeast striking, high angle normal faults (terminal faults), (4) northeast trending, 'slice' faults and (5) crossfaults. The northeast striking, high angle normal faults pose the greatest obstacle to systematic exploration and mining, as these faults are commonly spaced a few metres apart dividing veins into short segments in a northwest-downward direction.

Vein-type mineralization of the Beaverdell camp is characterized by a high silver content. Mineralization is composed of galena, sphalerite and pyrite with lesser amounts of arsenopyrite, tetrahedrite, pyrargyrite, chalcopyrite, polybasite, acanthite, native silver and pyrrhotite. The gangue minerals in veins are mainly quartz with lesser amounts of calcite, fluorite and sericite with rare barite. 'Ore ground' has been described as propylitic altered granodiorite, quartz diorite and quartz monzonite of the Westkettle batholith, up to 15 metres wide. These zones are characterized by sericite, clay minerals, chlorite, calcite, epidote and hematite. The fault-bounded veins commonly have a banded texture defined by outer, crudely parallel sulphide stringers. The wallrocks are brecciated and sheared over 30 to 150 centimetres width adjacent to veins. Weak sericite alteration of feldspars is pervasive in the Westkettle batholith.

The interpretation of galena lead-lead isotope age data coupled with geometrical and age relationships between dikes and veins suggests mineralization was formed around 50 Ma, coeval with Eocene stocks (Canadian Journal of Earth Sciences, Vol. 19, No. 6, pages 1264-1274, 1982).

The Highland Lass vein system averages 13 centimetres width. The system is funnel-shaped and widens to the west. In plan view, the vein system is composed of a series of faulted ore shoots, elongate along strike and en echelon downdip. In general, in the upper part of the vein system there is a higher gangue content in the veins than in the Lower Lass. There are no strong trends between gangue content or vein thickness and silver values. Gold-silver zonation is present in the system with silver values highest in the higher parts of the system and centrally between the hangingwall and footwall. This is supported by fluid inclusion data indicating temperatures of 180 to 260 degrees Celsius, less saline (less than 15 per cent) and lower pressure solutions (Watson, 1981). Gold is concentrated at depth in the system and in several small locations along the system footwall and supported by fluid inclusion temperatures of 260 to 310 degrees Celsius, 15 per cent salinity and high pressure solutions (Watson, 1981). Elemental correlations were found between silver content and galena, sphalerite and antimony sulphosalts (Watson, 1981). Gold is associated with pyrite and chalcopyrite (Watson, 1981). The Highland Lass vein system is characterized by high silver values, moderate zinc and lead values, more gangue and thinner veins than the Lower Lass system, and multiple vein and stringers zones. An Idaho-type dike zone is well exposed on the No. 8 level of the Highland Lass. The zone is composed of numerous subparallel slice faults and faulted segments with one or more dikes. The overall strike of the zone is 090 degrees and dips southeast somewhat more steeply than the Lass vein system.

Seven stages of mineral paragenesis have been recognized in the Lass vein system with many veins containing one or more of the following stages from oldest to youngest: (1) quartz-pyrite and minor sphalerite, (2) pyrite brecciation and replacement by arsenopyrite, (3) dark sphalerite with emulsions of chalcopyrite, (4) main depositional stage of galena, light sphalerite with little or no chalcopyrite, (5) silver minerals closely associated with galena including pyrargyrite, tetrahedrite and polybasite, (6) late gangue (mainly quartz) and (7) minor silver supergene mineralization.

Production from the Highland Lass commenced in 1922 and continued annually from 1928 to 1936. During this period, 4735 tonnes was mined with 30,925,029 grams silver, 5940 grams gold, 313,371 kilograms lead and 487,528 kilograms zinc were recovered. After 1936, production figures were combined with the Highland-Bell mine. The Highland Lass was developed by nine levels in a fault block about 396 metres wide in an east-west direction and bounded by the East and West Terminal faults. Ore shoots were continuous over horizontal distances of up to 152 metres and 30 metres updip, which were followed to the contact between granodiorite and the Wallace Formation. The largest and richest stopes were reported to be within 120 metres of this contact.