The May is located at about 915 metres elevation on the west side of the West Kettle River, 7.5 kilometres south-southwest of Beaverdell.
In 1970, an exploration program was carried out by Canex Aerial Exploration Ltd. A 9-tonne shipment of ore is recorded for that year. Since 1972, the property covering the occurrence has been owned and explored by Argentia Mines Ltd. In 1973, Rio Tinto Exploration Ltd. acquired an option on the property and Argentia Mines Ltd. made a shipment of 54 tonnes of crude ore (two truck loads) to the Trail smelter. In 1984, the occurrence was part of a large claim group held by Canstat Petroleum Co. The occurrence was located on the May claim and three diamond-drill holes were drilled.
Hornblende granodiorite to quartz diorite of the Middle Jurassic Nelson intrusions is centred on and underlies most of the Beaverdell area. This batholith has been intruded by porphyritic biotite quartz monzonite of the Cretaceous to Tertiary Okanagan batholith and contains remnants of pendants and/or screens of tightly folded metamorphosed volcanic and sedimentary rocks of the Carboniferous to Permian Anarchist Group, the oldest unit in this area. These rocks consist of regionally greenschist metamorphosed andesitic tuffs and lavas, mafic intrusions, hornfels and a minor amount of limestone. The Eocene Beaverdell porphyry is a subcircular granitic stock centred 14 kilometres south of Beaverdell. It is mostly exposed on the northeast side of the Kettle River, in the Dominion Creek drainage, west of Boyer Creek and south of the mouth of Tuzo Creek. The stock has been dated by potassium-argon dating on biotite at 49.4 +/- 0.7 Ma. Satellite dikes and the stock itself intrude granodiorite phases of the Okanagan batholith and basal Tertiary rhyolite and conglomerate containing clasts of the Okanagan batholith, in the headwaters of the Dominion Creek.
Five separate rock units have been mapped locally at the May occurrence and surrounding area. The major rock type is an irregular mass of the porphyritic quartz monzonite. It occurs as small stocks and dike swarms. It is characterized by coarse (2.54 to 10 centimetres length) sanidine and smaller quartz phenocrysts in a groundmass of plagioclase, orthoclase quartz and minor biotite. This intrusion is generally barren of copper, lead and zinc sulphide mineralization. Minor pyrite occurs associated with sericite and carbonate alteration of plagioclase and sericite, chlorite, carbonate alteration of biotite. Granodiorite is medium grained and varies in composition from quartz monzonite to quartz diorite. Plagioclase, quartz, orthoclase and hornblende with minor biotite and magnetite comprise the granodiorite. A post-mineral hornblende-feldspar trachyte dike extends through the occurrence area. The oldest rocks are intensely deformed andesitic greenstone with felsic banding of the Anarchist Group. Porphyritic granite of the Beaverdell porphyry outcrop to the south of the occurrence.
The most obvious local structure feature is the northeast trend of the porphyry dike swarm, hornblende feldspar porphyry dike and attitude of the molybdenite zone at the nearby Mo occurrence (082ESW058). The most prominent fracture orientation strikes 040 degrees and dips steeply northwest and southeast. Others strike 290 degrees and dip north or 350 degrees with a 50 to 60 degree dip to the west. A major fault is implied by the offset of the hornblende feldspar porphyry dike across the West Kettle river valley. A right-lateral displacement of 300 metres is indicated.
Three distinct alteration environments have been identified. The most significant consists of hydrothermal alteration along the southern limits of the granodiorite and within 600 metres of the contact between the granodiorite and the Beaverdell porphyry. Minor alteration also occurs adjacent to the Beaverdell porphyry contact, over up to 61 metres width. Sericite-clay and chloritic alteration of the granodiorite and quartz monzonite prevail. To the west, alteration of the quartz monzonite consists of silicification and k-feldspar flooding, chloritization of mafics and minor pyrite and molybdenite. For a more detailed description of this latter alteration refer to the Mo occurrence (082ESW058).
Sphalerite, galena, chalcopyrite and cuprite with associated oxides and carbonates have been identified in altered granodiorite. Malachite occurs mainly as halos around copper sulphides, and aurichalcite (a hydrous zinc-copper carbonate near surface on joints and fractures) have been identified. Copper mineralization frequently occurs separately from lead-zinc mineralization, although trace copper sulphides can be found with the latter. The mode of occurrence is either as disseminations or as small clots in hairline quartz veinlets. The best mineralization trends northeast, paralleling and 600 metres north of the granodiorite-porphyry granite contact. Silver occurs in varying amounts, probably occurring in either argentite or tetrahedrite inclusions in galena. Surface oxidation of mineralized zones extends to 1.5 metres depth.
Of three drillholes drilled in 1983, hole 1983-16 returned the best assay results. The hostrock was granodiorite. The 0.5-metre interval between 46.07 and 46.47 metres yielded 6.85 grams per tonne silver, 1.54 per cent lead and 2.00 per cent zinc (Assessment Report 12734). In the same hole, the 0.5 metre interval between 58.55 and 59.05 metres yielded 0.38 per cent lead and 0.44 per cent zinc. Assay values from earlier trenches yielded grades from 1 to 2 per cent zinc, 0.5 to 1.0 per cent lead, 0.10 copper and 3.42 grams per tonne silver (Assessment Report 4385).
The 63 tonnes ore shipped in 1970 and 1973 produced 6127 grams of silver, 1497 grams of gold, 117 kilograms of lead and 63 kilograms of zinc.