The Killarney past-producing mine is located on Lot 4637, approximately 2 kilometres northeast of Lightning Peak.

The Lightning Peak area is underlain by limestone and greenstone of the Devonian-Triassic Harper Ranch Group. These are underlain and intruded by granodiorite and diorite of an unnamed Middle Jurassic intrusion. Quartz porphyry dikes are common in the Harper Ranch Group; pegmatitic variations are sometimes associated with mineralization in the Lightning Peak camp. Several remnants of Miocene-Pliocene Chilcotin Group plateau basalts are found in the area, including the summit of Lightning Peak.

The occurrence consists of mineralized quartz veins following west-trending factures or shears exposed in several short adits and trenches. The veins have a general west to northwest strike and a north to northeast dip. Mineralization in the veins consists of streaks and small lenses of argentiferous galena with minor amounts of sphalerite, pyrite and chalcopyrite. The veins vary in width from several centimetres up to approximately 30 centimetres. Faulting of the veins is extensive, with each successive segment thrown northward. The vein, or veins, exposed on the Killarney property are similar to those of the Waterloo (MINFILE 082ENE017) mine 4 kilometres to the northwest and to the Lightning Peak (MINFILE 082ENE035) occurrence 300 metres to the southeast.

In 1922, a sample of massive sulphide from the property assayed 0.68 gram per tonne gold, 2121 grams per tonne silver, 60 per cent lead and 4 per cent zinc (Minister of Mines Annual Report 1922, page N172).

A sample, taken in the 1950s, from a 15-centimetre wide mineralized vein assayed 177.8 grams per tonne silver (Property File - Unknown [Unknown]: Report - Lightning Peak Area).

In 1967, a sample (no. 93165) of mineralized lens from a short adit assayed 13.7 grams per tonne gold, 2448.7 grams per tonne silver, 1.06 per cent zinc and 6.86 per cent lead (Property File - J.C. Stephen [1967-10-20]: Report - Lightning Peak Area - Mastodon Highland Bell Mines Ltd.).

More recent work, in the 1980s, identified a mineralized structure exposed for approximately 30 metres in trench L-11. The zone strikes 309 degrees and dips 74 degrees to the northeast, and is thought to be an extension of the mineralized zone that was mined in the old underground workings a short distance to the east. In 1983, a grab sample from a 12-centimetre wide quartz vein in andesite containing galena and sphalerite assayed 335 grams per tonne silver, 0.08 per cent lead and 0.04 per cent zinc, whereas a grab sample of a pyritic quartz porphyry dike exposed in trench L-8, a short distance to the south of the adits, assayed 1.7 grams per tonne gold (Assessment Report 13356).

The Killarney claim was staked in 1918 and Crown granted in 1925, as Lot 4637, to W.J. Banting of Edgewood. In 1919, a trial shipment of 1 tonne of hand-picked, mineralized talus was shipped to the Trail smelter. It produced 2177 grams of silver and 360 kilograms of lead. Prior to 1922, work consisted of two adits, 8 and 15 metres long, respectively, that did not locate the vein.

During the 1920s and early 1930s, numerous programs were carried out on the property, with little success. A 35-metre crosscut failed to intersect the vein; a drift in another adit lost the vein after 14 metres. At least five adits and several trenches were completed in an effort to follow the faulted vein segments. The lack of continuity of the vein structure appears to have been the main obstacle. This period of exploration and development on the Killarney ended in approximately 1935.

In 1959, H.O. Cooper produced 4 tonnes of crude ore from the Killarney property, presumably from the old dumps and talus. The ore yielded 14 090 grams of silver, 1133 kilograms of lead and 38 kilograms of zinc. No further details about this operation are available. In 1967, Mastodon-Highland Bell Mines prospected and sampled the area.

In 1983, Mohawk Oil Company Ltd. optioned the Killarney property and carried out a program of geological mapping, trenching and geophysical surveys (magnetometer, VLF-EM and self-potential). A total of 12 trenches were excavated, the most significant of which was trench L-11. The geophysical program identified a number of anomalies, including some associated with mineralized structures. In 1992, Zalmac Mines completed a program of geological mapping, soil and rock sampling, surveying and aerial photograph studies on the area as the P and Z claims.