The Shamrock occurrence is situated immediately north of Erie Lake, approximately 1 kilometre north of Highway 3, 2 kilometres east of the historic Arlington mine and 3 kilometres west of Salmo. An old logging road ends at the Shamrock vein and the Maybee vein is situated approximately 400 metres uphill of the Shamrock vein.
The area is underlain by Early Jurassic Rossland Group rocks intruded by phases of the Middle Jurassic Nelson Batholithic Suite. Within the Rossland Group, the Archibald Formation, a sequence of fine to coarse sediments, is overlain by the volcanic rocks of the Elise Formation and the mainly fine-grained clastic rocks of the Hall Formation. The Archibald Formation ranges from interlayered argillites and siltstones (exposed at the Maybee vein) to dark, laminated rusty argillites interlayered with occasional augite phyric flows marking a gradational contact with the overlying Elise Formation. The Elise Formation is subdivided into a basal unit of mafic flows and flow breccias overlain by a thick accumulation of intermediate pyroclastic rocks. To the south, exposures of the Lower Elise contain massive augite-phyric flows, flow breccias and heterolithic to mafic clast-dominated volcaniclastics interbedded with well-layered, mafic water-lain tuff beds. To the north, the Elise is dominated by well-layered fine to lapilli tuffs interlayered with dark graphitic argillite and dark grey argillaceous siltstone.
To the north, the southern edge of the Bonnington Batholith, part of the Nelson Plutonic Suite, is exposed, as is a small granitic stock in the valley to the south. Exposures of the Bonnington Batholith consist of potassium-feldspar porphyritic to locally massive granodiorite cut by felsic dikes.
Several generations of faulting have been recognized in the area. North-trending, east-verging thrust faults occurring to the south and southeast are cut by Cretaceous and Middle Jurassic plutons. Parallel, north-northeast–trending faults occurring to the south cut earlier folds and are cut and sealed by Jurassic plutons. Steeply dipping, northwest-trending extensional faults running through the centre of the Sadarsa property cut both earlier structures and Jurassic plutons.
The Shamrock occurrence lies within the Shamrock zone on the Sadarsa property. The zone covers an area containing both the Shamrock and Maybee (Shamrock North) veins.
The Shamrock vein is hosted within a small granitic stock exposed in the Beaver Creek–Erie Lake Valley. The stock, believed to be related to the Wallace Creek stock to the east, is offset by several prominent northwest-trending faults and comprises a medium-grained, light grey biotite granite or granodiorite containing numerous aplitic dikes along the northern margin. The Shamrock vein is typically banded (sheared) in texture.
The Shamrock vein has been traced through surface trenching with only minor underground exploration in shallow shafts. A large historic trench has exposed an east-northeast–trending quartz-gold-sulphide vein system along its entire length. The attitude of the vein system varies along strike from a strike of approximately 60 degrees at the western end to 75 degrees at the eastern end. The vein system consists of a shear zone up to several metres wide containing a prominent quartz-gold-sulphide vein and numerous thinner splays of veins in the hanging wall of the main vein. The main vein is of variable thickness (ranging from 20 to 60 centimetres) and contains mainly brecciated quartz with carbonate and varying amounts of pyrite, galena and localized sphalerite. Gold and silver content varies throughout and silver is typically associated with base metals.
To the north of the stock, the Maybee vein occurs within metasediments of the Archibald Formation, in a well-exposed section of interlayered argillites and siltstones cut by aplitic dikes. Based on exposures in shallow pits, the strike length of the vein has been extrapolated to approximately 200 metres. Exposures of the vein comprise mainly quartz with pyrite, considerable jarosite alteration and variable iron carbonate. Unlike the Shamrock vein, the Maybee vein is typically brecciated in texture.
Considerable evidence of past exploration at the Shamrock occurrence includes some caved adits, a shaft and a 200-metre-long trench. This exploration activity occurred prior to 1988 and does not appear to be documented. At the north end of the Maybee vein, evidence of past exploration includes several vertical shafts and the presence of considerable dump material.
Prior to 1902, the Transvaal and Zambesi Mining Company conducted development work on the Armstrong claim group (MINFILE 082FSW267), consisting of the Armstrong, Erie and Black Knight claims, to the west of the Shamrock occurrence. The property was dormant from 1902 until 1928, when the claims were acquired by S.E. Coulter and P. Coulter. The old tunnels were cleaned out and the trail to the property was opened up. The workings, situated on the Black Knight claim, consisted of open-cuts and four tunnels. The tunnels developed four widely separated silicified fractured zones in granite.
In 1978 and 1979, Salmet Resources Corporation staked the Dan, Dan 2 and Dan 3 claims over the southern half of the modern Sadarsa property. The claims were held as part of the Silverhorn property. In 1980, Salmet Resources conducted a program of geochemical sampling, geophysical surveying and trenching on the Silverhorn claims to the immediate east.
The first record of exploration on the Sadarsa property was in 1981 on the Key claim to the west of the Dan and Armstrong claim groups. The Key claim covered an area containing the Meadows occurrence (MINFILE 082FSW268). Rick Wierzbicki carried out a limited molybdenum exploration program on the property, collecting two geochemical samples.
In 1983, Taiga Consultants Limited, on behalf of Rex Silver Mines Limited, conducted reconnaissance mapping, prospecting, sampling, soil geochemistry and ground geophysical surveying on the ORC claims to the north. Five samples were collected from the Erie Creek showing.
In 1989, a very low-frequency electromagnetic geophysical ground survey was conducted over the DC, Bear and Poogy claims to the immediate west of the historic Armstrong claim group (MINFILE 082FSW267). Following this survey, 117 soil samples were collected between 1989 and 1990. In 1990, a grid was established over the southeastern portion of the claim group. A total of 5.2 line kilometres of ground geophysical surveying were completed and 66 soil and eight rock samples were collected and sent for analysis.
In 1989, the northeastern portion of the modern Sadarsa property was staked as the Erie Creek property. Between 1989 and 1990, Desert Gold Resources Incorporated conducted an exploration program of geological mapping, geophysical surveying and soil, silt and rock geochemistry on the Erie Creek claim group.
In 1990, a program of prospecting, mapping, showing and outcrop sampling and geophysical surveying was completed on the Shamrock claim group by claim owners R. Bourdon and C. Pittman. A total of 29 samples were collected in the immediate vicinity of the Shamrock and Maybee veins.
Also in 1990, R. Jordan conducted a mapping and prospecting traverse across the Sherman claim to the west of the Shamrock zone and immediately east of the Armstrong claim group (MINFILE 082FSW267). The following year, Jordan followed up the mapping and prospecting program by collecting 23 soil samples on the Sherman claim and 35 samples on the RR claim to the immediate north of the Shamrock zone.
In 2007, D. Lavoie staked the Sadarsa claim group. That same year, prospector Tom Kennedy conducted a small rock geochemistry program on the property, collecting 42 rock samples. As a follow-up to the rock sampling program, Robert Klewchuk Limited was commissioned to conduct a soil sampling program on the property in 2008. Samples were collected over two grids—one to the southwest of the Erie Creek showing in the northern portion of the property and the other slightly north of and between the Meadows (MINFILE 082FSW268) and Shamrock occurrences in the southwestern portion of the property. Between 2009 and 2010, Kennedy conducted another rock geochemistry program, collecting 22 samples from both outcrops and float from an area to the east of the Shamrock vein in the southeastern corner of the property. Later in 2010, an additional nine samples were collected from the southwestern corner of the property from an area between the Meadows (MINFILE 082FSW268) and Armstrong (082FSW267) occurrences.
In 2011, Trygve Hoy, on behalf of Kootenay Gold Incorporated (also referred to as Kootenay Silver Incorporated), conducted a short program of geological mapping and sampling on the property. Seven samples were collected from the Meadows occurrence (MINFILE 082FSW268), 20 from the Shamrock vein, four from the Maybee vein and one from a new vein exposed approximately 1 kilometre west of the Shamrock vein. That same year, Tom Kennedy collected 65 rock samples across the southern portion of the Sadarsa property.
In 2012, Kennedy carried out a 34-sample rock geochemistry program over the Shamrock zone. Sampling was focused in the area of the Shamrock vein and to the south of the Maybee vein.
Sample 30005, collected at the Shamrock vein by Bourdon and Pittman in 1990, returned 2.24 grams per tonne gold, 212.3 grams per tonne silver, 2 per cent lead and 4 per cent zinc (Assessment Report 20208, page 6).
From the 2009 and 2010 sampling program, the most significant results were from sample TK09-259 with 30.76 grams per tonne gold and sample TK09-004 with 9.783 grams per tonne gold (Assessment Report 31606, page 10). The best gold result from Tom Kennedy’s 2011 sampling program was sample TK11-017 taken from the Shamrock vein, which returned 87.831 grams per tonne gold (Assessment Report 34282, page 10). Samples TK12-013 and TK12-015, taken from the Shamrock vein in 2012, returned 33.935 grams per tonne gold and 14.206 grams per tonne gold, respectively (Assessment Report 33311, page 11).
In 2011, a grab sample of vein material from a historic adit on the Maybee vein returned 6.45 grams per tonne gold and 1.8 grams per tonne silver, and a sample of dump material returned 2.726 grams per tonne gold, 17.2 grams per tonne silver and 1.23 per cent lead (Assessment Report 32900, page 21). From the Shamrock vein, a grab sample of vein material returned 27 grams per tonne gold, 25.3 grams per tonne silver and 0.97 per cent lead (Assessment Report 32900, page 20).
