The Skylark claim is centred 2.7 kilometres east of Greenwood and 0.8 kilometre southeast of Twin Creek, at the elevation of 1140 metres. Access is 1.8 kilometres easterly by winding dirt road from the main Greenwood to Phoenix road.

The Greenwood-Grand Forks area contains late Paleozoic and Mesozoic volcanic and sedimentary rocks, mainly in the greenschist facies of regional metamorphism, which are intruded by Mesozoic plutons and unconformably overlain by Tertiary volcaniclastic and flow rocks. The pre-Tertiary stratiform rocks are contained in a series of five, north dipping thrust slices with bounding faults, which at many places are marked by layers and lenses of deformed serpentinite. These thrust slices lie above high grade metamorphic complexes.

The Upper Paleozoic rocks in the Greenwood area are Devonian to Permian Knob Hill Group chert, greenstone and related diorite and serpentinite and Carboniferous to Permian Attwood Group dark-grey argillite, limestone and minor volcanic rocks. They are unconformably overlain by the Brooklyn Formation of clastic sedimentary rocks, limestone and largely submarine pyroclastic breccias and related dioritic intrusions. These rocks probably formed in an environment of growth faulting and explosive volcanism (Open File 1990-25).

The distribution of the Tertiary rocks is controlled by a complicated array of extension faults. Three sets are recognized. The oldest are gently east-dipping, at or near the base of the Tertiary. Later, dominantly west-dipping, listric normal faults have caused rotation so that the Tertiary strata dip to the east at moderate angles; the apparent offset on each of the five of these faults is measured in kilometres. The third and latest faults are north to northeast-trending, steeply dipping, strongly hinged and influenced by the earlier faults.

The Skylark property is underlain by a sequence of northwest-trending volcanic and sedimentary rocks of the Carboniferous or Permian Attwood Group intruded to the west by granodiorite of the Cretaceous Greenwood stock (Nelson Intrusions). The predominant rock type is argillite, which strikes northwest and dips 35 degrees northeast. A sequence of andesitic volcanic rocks is found to be overlain by the argillite, which in turn is overlain by bedded chert.

Locally, a number of mineralized zones have been identified on the Skylark (L.763) Crown grant, the Meadow Lark (L.1712) Crown grant, the Iron Cap (L.1574) Crown grant, the Silver King (L.1097) and Silver Cloud (L.1218) Crown grants and the Billy Fraction (L.999) Crown grant, including the H zone and Serp zones.

The Skylark mine is located on a quartz vein in argillite near the east boundary of the Greenwood stock. The Skylark vein strikes approximately 020 degrees and dips 52 degrees east. It has been traced for greater than 200 metres by surface and underground workings. In the old stopes, the maximum reported width of the vein was 0.76 metre. The values commonly occur as ‘pay streaks’ near the hangingwalls and footwalls. The pay streak near the hangingwall is generally larger. Widths on the pay streak it average 15 to 20 centimetres but a width of 38 centimetres is reported at one point. The mineralization has been described variously as fine-grained, steel-grey galena accompanied by tetrahedrite and ruby silver; solid arsenopyrite with fine-grained galena and sphalerite; and pyrite, silver bearing stibnite and native silver. Argentite has also been reported. The ore is easily mined and readily breaks free from the wallrocks. The vein occurs in a zone of intense silicification and carbonatization.

In 1969, diamond drilling from a trench, located approximately 60 metres south of the shafts, is reported to have intercepted the mineralized vein, yielding from 0.2 to 2.4 grams per tonne gold, 15.7 to 201.8 grams per tonne silver with less than 0.5 per cent combined lead-zinc (Property File - Alrea Engineering Ltd. [1975-07-22]: Preliminary Examination - Skylark Property). The holes tested the vein along strike to a depth of approximately 4.5 metres.

In 1975, a sample of arsenopyrite-pyrite bearing calcareous argillite from the area of the Skylark shafts assayed 2.7 grams per tonne gold and 0.26 per cent copper, whereas sampling of a trench exposing the vein, approximately 60 metres south of the shafts, yielded up to 25.7 grams per tonne gold, 593.4 grams per tonne silver with 1.19 per cent lead from a 7.5-centimetre wide vein in the floor of the trench and 10.9 grams per tonne gold with 685.7 grams per tonne silver over 1.2 metres from the hangingwall of a 30-centimetre wide vein (Property File - Alrea Engineering Ltd. [1975-07-22]: Preliminary Examination - Skylark Property). Another trench, located approximately 150 metres south of the shafts, exposed a pyrite-bearing calcareous argillite yielding up to 3.4 grams per tonne gold (Property File - Alrea Engineering Ltd. [1975-07-22]: Preliminary Examination - Skylark Property).

The H zone, located to the southwest on the Billy Fraction (Lot 999) and discovered in 1984, is hosted by an andesite dike system intrusive into granodiorite along north-trending fractures. This is likely a segment of the vein faulted from the south end of the earlier mine workings. The orebody itself is contained in a fault within an andesite dike. The fracture/fault structure strikes 040 degrees and dips 50 degrees to the southeast. Mineralization consists of fine-grained, banded sulphides with a variable quartz content (10-40 per cent). The vein matter varies from 2.5 to 60 centimetres in width but averages 10 centimetres. Sulphide mineralization consists of pyrite, hematite, sphalerite, galena, chalcopyrite, pyrargyrite, proustite and native silver. Locally, both hangingwall and footwalls display fault breccia and gouge. Many subparallel faults have caused the ore zone to pinch, swell and locally be sheared.

In 1986, measured reserves for the H zone were reported at 77 103 tonnes grading 685.6 grams per tonne silver and 2.74 grams per tonne gold (Assessment Report 15731). In 1989, remaining reserves were reported at 25 162 tonnes grading 752.7 grams per tonne silver and 3.35 grams per tonne gold (Property File - Viscount Resources Ltd. [1989-07-04]: No. 127 (1989) - O.B. Silver Gold Mine Operations Reviewed).

The Serp zone occurs below the southwest part of the H zone and cuts the main shear structure at an oblique angle. The Serp zone is identified by the presence of serpentine, chlorite, carbonate and talc. This serpentinite is an erratic, nonplanar zone of variable thickness and orientation, with an indicated trend of 330 degrees that dips approximately 35 degrees east. The Serp zone is found intercalated with andesitic volcanic rocks that are within the granodiorite. The Serp zone contains variable high gold and silver values associated for the most part with narrow (1-6 centimetres) pyrite veinlets; native gold is also observed. The zone has been traced by diamond drilling over a thickness of approximately 36 to 39 metres.

During 1985 through 1987, drilling on the Serp zone yielded intercepts of 14.7 grams per tonne gold over 4.05 metres in hole 85-13, with an average value of 6.3 grams per tonne gold over 2.64 metres in holes 85-12, 13 and 19 through 22; 39.3 grams per tonne gold over 0.45 metre in hole SPN-86-1; 60.3 grams per tonne gold over 0.3 metre in hole SPN-86-6, which included a narrow section of pyrite and free gold, and 12.7 grams per tonne gold over 9 metres from a reverse circulation drill hole (Property File - Skylark Resources Ltd. [1987-11-18]: News - O.B. silver mine - Skylark property). In 1989, underground drilling on the zone yielded up to 112.9 and 82.1 grams per tonne gold over 1.2 metres, respectively (Property File - Skylark Resources Ltd. [1989-06-09]: No. 111 (1989) - New Gold Zone to be Opened Underground).

On the Meadow Lark (L.1712) Crown grant, located immediately south of the Skylark Crown grant, a series of parallel to subparallel, east-west–trending quartz veins hosted by rhyolite or silicified meta-sandstone and greenstone or andesite are exposed by a series of trenches. In 1985, sampling of a vein in greenstone and/or andesite from the main trenching area yielded 144.0 grams per tonne silver and 0.9 gram per tonne gold over 0.3 metre, whereas two other trenches, located approximately 150 and 200 metres further to the south-southeast, expose two more veins in greenstone or andesite and yielded 203.1 and 472.3 grams per tonne silver with 7.2 and 1.7 grams per tonne gold over 15 and 12.5 centimetres, respectively (Property File - Skylark Resources Ltd. [1985-06-01]: Map - Plan Showing Claims, Geology and Surface Features - Skylark group).

On the Iron Cap (L.1574) Crown grant, an oxidized zone in greenstone or andesite is exposed by a former trench or short adit. In 1936, a sample of siliceous-pyrrhotite ‘ore’ from the Crown grant is reported to have assayed 5.8 grams per tonne gold, 30.8 grams per tonne silver, 0.58 per cent copper, 0.41 per cent zinc and 24 per cent lead (Property File - D.B. Morkill [1963-07-12]: Letters and Reports on the Bay Fraction and Adjoining Claims).

On the Silver Cloud (L.1218) and Silver King (L.1097) Crown grants, located further to the west, a chloritic andesite hosts up to 30 per cent pyrrhotite as irregular lenses and disseminations. The mineralization is exposed by several short pits, trenches and adits over an area of approximately 30 by 90 metres. A north-south–striking quartz vein, traced for over 200 metres, is also reported.

The Skylark claim was staked in 1893 by S. Bloyer and mined in the early years with some good results. The Skylark (Lot 763) and Denver (Lot 764) claims were Crown granted to G. Lavagnino in 1898. The focus of interest on the Skylark claim is a mineralized quartz-carbonate vein in argillite and greenstone units of the Attwood Group. The vein has been worked mainly from two inclined shafts, dips 52 degrees southeast, averages 15 to 20 centimetres wide, and has a strike length of approximately 200 metres. The deeper shaft, which was completed in 1906, is 60 metres deep, plunges approximately 55 degrees to the east, and follows the vein to a depth of 24 metres, where it is displaced easterly approximately 9 metres by a flat-lying fault. The vein was picked up again by a crosscut, and a winze was sunk on it to a depth of approximately 10 metres. On the 24-metre level of the mine, a drift was run on the vein for approximately 75 metres following a north-south structure.

Mining on the Skylark claim during the period from 1893 to 1940 was intermittent, with the greatest production attained during 1905 to 1907 and 1915 (Skylark Development Company Limited), and in 1935 (W. McArthur). Total ore shipped for this period amounted to 1866 tonnes having 5282 kilograms of silver, 22.5 kilograms of gold, 25.8 tonnes of lead, and 4.8 tonnes of zinc. More recent production, in 1988 and 1989 (Skylark Resources Ltd.), added an additional 33 298 tonnes, with recoveries of 11 751 kilograms of silver, 90 kilograms of gold, 9536 kilograms of copper, 107 538 kilograms of lead and 43 608 kilograms of zinc.

The Last Chance (MINFILE 082ESE216) occurrence and adjacent claims were held in 1969 as part of Mineral Lease ML 277. Work by Sarco Investments Ltd. was confined mainly to the Skylark and included five short drillholes, totalling 31.95 metres. In 1974, H.H. Shear held the Last Chance and Skylark; work was confined to the Skylark. The lease lapsed and the Last Chance was optioned from J.A. MacLean by Greenwood Explorations Ltd. in 1975.

In 1980, the mine was re-activated and the Skylark vein was worked along strike for 150 metres and stoped downdip for 60 metres. In 1986, a decline ramp was driven for 172.8 metres to the H zone along with a 10.6-metre raise to the 80.7 metre (no. 1) level on the H zone and three more raises from this level, totalling 122.9 metres. In 1987, the decline was extended to 458 metres and a second, lower level (no. 2) was established 45.7 metres downdip of the first level. A crosscut and raise were driven to the S-1 level of the Serp zone for approximately 85.5 metres to the west, and a drift (S-2) and second level (S-3) were started. Also at this time, eight underground drillholes, totalling 160.8 metres, were completed. In 1988, a total of 351.8 metres of decline and 348 metres of excavating, including raises, was completed on the H zone, and 189 metres of excavating was completed on the Serp zone.

Production from the H zone began December 7, 1987, at 90 tonnes per day, the ore being shipped to the Robert Mines Ltd. mill some 4 kilometres south of Greenwood. Mining operations ceased in early 1989. During this period, total production was increased by 33 298 tonnes, with recoveries of 11 751 kilograms of silver, 90 kilograms of gold, 9536 kilograms of copper, 107 538 kilograms of lead, and 43 608 kilograms of zinc.