The Dorothy occurrence is located southwest of Sandon at 1463 metres elevation above sea level in the Slocan Mining Division. The property includes the Dorothy Crown grant (Lot 2034) and the Irene Fraction Reverted Crown grant (Lot 4530). It lies along the west side of the Ruth-Hope property (082FNW052).
Very little of the history of the development of this property has been recorded. It was Crown-granted to the Ruth No. Two Mining Co. Ltd. in 1899.
The owner of the claim in 1926 was J.P. Wilson of Sandon and apparently some of the development work was done by him at about this time. In 1935 the claim was reported owned by C.B. White of New Denver. About 1952 the claim was owned by Kelowna Exploration Co. Ltd. The upper workings were reported to be caved at this time.
The property is developed by two adits, the one 38 metres lower than the other. The lower adit, was driven 67 metres at south 60 degrees east to a raise driven upwards at 30 degrees. A 30-metre branch to the northeast ends in another short raise.
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 Dorothy occurrence is hosted by thinly bedded argillite and quartzite of the Slocan Group. The sedimentary rocks typically contains up to 3 per cent graphite. Limonite is present in the exposed outcrops and is derived from the oxidation of pyrite. Many small fractures striking 130 to 150 degrees and dipping 35 to 75 degrees northeast cut the sedimentary sequence. Many small veins of calcite and quartz with minor pyrite are present throughout the sequence and disseminated pyrrhotite is common.
Two fissure vein structures are present on the Dorothy property, the Minnie Ha Ha and the Dorothy vein. The Silvana (082FNW050) Main vein passes just south of the Irene Fraction Reverted Crown grant. The Minnie Ha Ha vein strikes east and dips 30 to 40 degrees south. The vein is exposed on the northern part of the Dorothy Crown grant. On the Dorothy property, the Minnie Ha Ha consists mostly of graphitic gouge with calcite and minor galena and sphalerite. The Dorothy vein strikes north and dips 60 degrees east. It is about 396 metres long and runs between the Minnie Ha Ha and the Silvana Main vein to the south. It has been explored with a short adit on the Dorothy Crown grant and surface trenches on both claims. The vein is brecciated and includes large blocks of argillite and quartzite in a matrix of massive calcite with minor siderite and pyrite. The vein contains thin but consistent bands of mineralization which include galena, sphalerite, anglesite and pyrite. A weighted average of four chip samples yielded 209 grams per tonne silver, 5.1 per cent lead and 6.3 per cent zinc. The samples were taken across a 1.1 metre width and over a 9 metre vein length (Assessment Report 15774).
On the Irene Fraction Reverted Crown grant, the vein is more sheared and brecciated than on the Dorothy Crown grant. It consists of 50 to 75 per cent calcite with minor siderite and pyrite with lesser amounts of galena and sphalerite.