The Gem occurrence is situated east of Little Spider Peak near the headwaters of Ladner Creek, approximately 1 kilometre southeast of the Pipestem mine (MINFILE 092HNW011). It represents the northernmost showing in the original Gem group of claims, which also encompassed the Golden Cache occurrence (MINFILE 92HNW048).
The area is underlain by grey to black, locally organic-rich, pyritic, slaty argillite intercalated with well-bedded siltstone, all assigned to the Early and Middle Jurassic Ladner Group. A number of northwest- striking bands of medium to very coarse-grained, tuffaceous, fossiliferous wacke also occur within the sequence. The bands vary from 5 to 45 metres thick and are the principal host to gold mineralization at the Pipestem mine.
In the area of the mine, these sedimentary rocks have been intruded by narrow sills and dikes up to 4 metres thick. Several porphyritic felsic sills, similar to those associated with gold occurrences in the Siwash Creek area (MINFILE 092HNW004, 005, 015-017), host thin quartz veins with pyrite.
Development at the Gem occurrence reportedly consisted of three open-cuts that exposed several parallel quartz veins striking 110 degrees and dipping steeply to the north and south. The veins were hosted by slate and were sparingly mineralized with pyrite and arsenopyrite. The principal vein, approximately 1.8 metres wide and dipping 70 degrees to the north, comprised decomposed quartz containing fragments of slate. The fragments had undergone silicification and were described as similarly mineralized with pyrite and arsenopyrite. Mineralization, where heavy, favoured the host slate, particularly along the hangingwall contact. Early reports also describe an altered "acid" sill as occurring along the hangingwall contact. Gold values in the veins were reported to be generally low, although systematic testing had not been carried out.
Red, "decomposed" earth overlying the northern cut reportedly contains pannable gold. Similar soil is present at the Murphy occurrence (MINFILE 092HNW037), 1 kilometre to the west. Several old pits and trenches in the immediate area of the Lorraine occurrence (MINFILE 092HNW079) may represent the Gem open-cuts.
In 1982, Carolin Mines completed a program of geological mapping, rock and soil sampling, trenching and 19 surface diamond drill holes, totalling 1721.51 metres, on the area. During 1994 through 1996, Athabaska Gold Resources completed programs of geological mapping and geochemical sampling on the area. In 2012, New Carolin Gold completed airborne magnetic and radiometric surveys, totalling 759 line-kilometres, on the area.