The Surprise occurrence is located at 2285 metres above sea level on Crown grant Lot 514. The property is on the ridge between Mount Payne and Reco Mountain in the Slocan Mining Division.
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 Surprise occurrence is hosted in a band of light coloured quartzite containing numerous quartz porphyry dikes. The dikes are fine grained and in some places are indistinguishable from the quartzite. Massive argillite and calcareous argillite of the Slocan Group are on either side of the band of quartzite and porphyry dikes.
The Surprise deposit consists of two fissure veins, the Main or Surprise vein and the Little vein. The Main vein strikes 065 degrees and dips 65 degrees southeast. It is a well-defined zone varying from a few centimetres up to 5 metres in width. The zone tends to steepen where it crosses massive quartzite or quartz porphyry dikes. The vein consists mainly of crushed wallrock, quartz and siderite. The ore, which consists of massive galena, is mostly hosted by quartzite and the quartz porphyry dikes. Sphalerite is usually restricted to the edges of the massive galena bodies. Galena contains inclusions of tetrahedrite whereas pyrargyrite is reported to occur in veinlets cutting across both galena and sphalerite. Pyrite and chalcopyrite are common accessory minerals. Where the vein crosses more argillaceous sedimentary rocks, the ore is restricted to narrow bands concentrated along the walls of the fissure which is mostly filled with crushed wallrock. The widest ore shoot, which has been stoped for about 130 metres downdip, appears to be associated with a series of pre-mineral shears that strike between 015 and 020 degrees and dip 50 degrees southwest. The Main vein is believed to be an extension of the Last Chance vein (082FNW020) exposed on Lot 717 about one kilometre southeast.
The Little vein is subparallel to the Main vein and about 30 metres to the northwest. The vein is only a few centimetres wide and consists mostly of sphalerite and quartz. Although the Little vein has been explored with a shaft and several adits, no production figures are available for this vein.
Production from the Surprise occurrence between 1893 and 1929 yielded about 59 tonnes of silver, 5606 tonnes of lead, 3537 tonnes of zinc and 124 grams of gold from 44,475 tonnes mined.
