The Jewel Lake area is underlain by a complex of metamorphic rocks mostly of sedimentary and volcanic origin correlative with the Carboniferous or older Anarchist Group, and a large granodiorite intrusion correlative to the Juro-Cretaceous Nelson Plutonic Rocks. Small dykes and sill-like bodies, feeders to nearby Tertiary lavas, pervade these units.
Locally the metamorphosed volcanic and sedimentary rocks are not always distinguishable, both being fine-grained and medium or dark coloured with primary structures such as bedding and flow banding being confused with foliation or gneissosity. Generally the sedi- mentary rocks are brittle and quartz-rich, however, compositions vary and some biotitic varieties have the same competence as the amphibole- rich volcanic rocks. These rocks are locally called quartzites but few are true quartzites and more appropriate terms would be quartz wacke or lithic wacke. The massive character of the volcanic rocks is due to a combination of intense regional metamorphism and primary structures. Field and petrographic data indicate that at least some of the original rock formed as a result of massive accumulations of lava flows and pillow lava. Crosscutting feeder dykes and sills are significant and contribute to the massive aspect of the volcanic rocks. The metamorphosed schistose volcanic rocks are compositionally basalts. These metasedimentary and metavolcanic rocks form part of the Carboniferous (Pennsylvanian-Mississippian) or older Anarchist Group.
Igneous intrusions in the Jewel Lake camp include a large Lower Cretaceous granodiorite pluton and a host of younger pulaskite and lamprophyre dykes. The granodiorite is correlative with Nelson Plutonic Rocks. It is a homogeneous medium-grained grey body which intrudes the metavolcanic rocks along a northwest trending contact in the southwest part of the camp. The intrusive has produced little effect in both the metavolcanic and metasedimentary rocks. Grano- diorite dykes occur and are compositionally similar to the main grano- diorite body and are probably offshoots from it. Pulaskite dykes are numerically most important. Several types are evident including both quartz-bearing and undersaturated types. Post-vein lamprophyre dykes as well as the pulaskite dykes are of probable Lower Tertiary age and cut all other major geological units.
The Moonlight claim (former Crown Grant) adjoined the Roderick Dhu claim (L.598, 082ESE125) to the north. A quartz fissure-vein is hosted in north-northeast striking and east dipping metasedimentary rocks of the Carboniferous (Pennsylvanian-Mississippian) or older Anarchist Group and are comprised of schistose quartz wackes or lithic wackes. The quartz vein appears to be in a fracture zone that roughly parallels the bedding/foliation planes of the host meta- sedimentary rocks. Open cuts and adits expose a quartz vein ranging in width from 25 to 61 centimetres sparsely mineralized with galena, pyrite and telluride.
In 1921, sampling on the Moonlight occurrence returned highlighted values of 3.43 grams per tonne gold, and 137.14 grams per tonne silver over widths ranging from 0.25 to 0.61 metres (Martin, D. (2016-07-12): National Instrument 43-101 Technical Report on the Gold Drop Property).
