The Last Chance occurrence is situated on Crown grant Lot 717 at 2165 metres elevation above sea level, in the Slocan Mining Division. The property is on the north side of Carpenter Creek northeast of Mount Payne.
The Last Chance and American Boy (082FNW081) adjoin and the mine workings are on the same lode system. The principal claims making up the properties were located in 1891 and were among the first to be staked in Slocan.
Development commenced on both properties in the early 1890's and continued at a fairly steady pace until 1908 when activity ceased. Work on the American Boy was carried out by Tom McGuigan and by the American Boy Mining and Milling Company, formed in 1897, later (1918) reorganized and renamed American Boy Mining Company. Work on the Last Chance was carried out by the Last Chance Mining and Milling Company.
In 1920 work recommenced on the Last Chance property and in 1922 on the American Boy. Activity was intermittent and lasted until about 1927. From that time until 1953 nothing was done on either property. In 1951 Cody-Reco Mines Limited bought up several properties in the Slocan area including the American Boy and Last Chance. A new road system was put in connecting the workings with a new mill built at Cody in 1952.
Workings on the main vein lode comprise 11 adits and several intermediate levels aggregating about 4.8 kilometres of drift and crosscut. These workings are connected by raises and explore the lode over a vertical depth of about 350 or 396 metres measured down dip. Most of the work was done on the main lode and only short crosscuts were required in any distance. Certain workings are continuous on the 2 properties and have developed the main lode a length of 823 metres.
In 1953 No. 9 adit of the American Boy was reopened and some drifting done. In 1954 about 106.6 metres of drifting to get around a cave on No. 9 adit level and raises were rehabilitated down to No. 10 and No. 11 levels. In 1960 Cody-Reco Mines Limited was reorganized and its name changed to Vespar Mines Limited.
Reco Silver Mines Limited in October 1968 acquired a lease, renewable every 4 years, on 21 claims in the Last Chance and Noble Five (082NW037) groups. Vespar amalgamated with Lakehead Mines Limited in January 1979 under the name Parlake Resources Limited. In May 1980 Reco Silver Mines changed its name to Silvex Resources Corporation.
Regionally, the area lies on the western margin of the Kootenay Arc, in allochthonous rocks of the Quesnel Terrane. In the vicinity of the occurrence, the Quesnel Terrane is dominated by the Upper Triassic Slocan Group, a thick sequence of deformed and metamorphosed shale, argillite, siltstone, quartzite and minor limestone. Rocks of the Slocan Group are tightly and disharmonically folded. Early minor folds are tight to isoclinal with moderate east plunging, southeast inclined axial planes and younger folds are open, southwest plunging with subhorizontal axial planes. The sedimentary sequence has been regionally metamorphosed to lower greenschist facies.
South of the occurrence, the Slocan Group has been intruded by the Middle Jurassic Nelson intrusions which comprise at least six texturally and compositionally distinct phases ranging from diorite to lamprophyre. The most dominant phase is a medium to coarse grained potassium feldspar porphyritic granite. Several feldspar porphyritic granodiorite dikes, apparently related to the Nelson intrusions, also cut the sedimentary sequence near the occurrence (Paper 1989-5).
The Last Chance occurrence is hosted by quartzite, argillaceous quartzite and calcareous argillite of the Slocan Group intruded by various dikes of quartz porphyry probably related to the Nelson intrusions. The sedimentary sequence generally strikes 120 degrees and dips 58 degrees southwest. For the most part, the sedimentary rocks are well bedded and banded. The quartz porphyritic dikes, in general, tend to follow the strike of the sedimentary rocks, and are 3 to 10 metres thick.
The occurrence consists of two or more fissure veins that cut across the sedimentary and intrusive rocks. The veins strike 045 degrees on the American Boy Crown grant and 060 degrees on the Last Chance Crown grant; dips are 60 to 65 degrees southeast. The veins have been explored for about 825 metres along strike and 400 metres downdip on both the American Boy and Last Chance Crown grants. The veins pinch-out to the southwest on the Chicago Crown grant where they cut fissile slate of the Slocan Group. The strike and dip of each fissure varies from point to point so that fissures meet and separate at irregular intervals developing a braided structure varying from a few millimetres to over 6 metres in width. The fissures are mostly filled with crushed wallrock. Argentiferous galena, sphalerite, pyrite, tetrahedrite and pyrargyrite occur with quartz and siderite concentrated in narrow veinlets near the walls of the fissures. The sulphide material is usually less than 10 centimetres wide except where crossfaults cut the fissure veins and pockets of massive sulphide up to 75 centimetres wide are developed. In general, sphalerite increases with depth.
Production from the Last Chance portion of the fissure vein structures between 1895 and 1922 amounts to about 33 tonnes of silver and 3493 tonnes of lead from 8448 tonnes mined.
