The En (Eureka Peak) occurrence is located on Eureka Mountain, approximately 8 kilometres north of Crooked Lake.
Regionally, the area lies along the eastern margin of the Quesnel Belt in south central British Columbia and is underlain by fine clastic sedimentary rocks of the Triassic Slocan Group and basaltic volcanic rocks and fine clastic sedimentary rocks of the Middle to Upper Triassic Nicola Group. These rocks form the upright northeast limb of the major northwesterly trending Eureka Syncline. Locally, the rocks form asymmetric drag folds that contain metamorphically derived quartz sweats in the hinges. Rotation of these folds by axial plane crenulation cleavage formed minor folds plunging slightly northwest of the earlier folds.
Locally, the area is underlain by meta-basalts, augite porphyry flows, pyroxene basalt breccias and tuffs of the Upper Triassic Nicola Group and phyllites of the Triassic Slocan Group. Lenses of granodiorite occur within the volcanic rocks while a sill-like pyroxenite body occurs near the base of the volcanic sequence.
Mineralization comprises chalcopyrite, pyrite and pyrrhotite as disseminations and in veinlets within intrusive, volcanic and sedimentary rocks, locally comprising up to 50 per cent of the host rock. In pyroxenite rocks sulphide exsolution blebs also occur. Wallrock alteration associated with copper mineralization is sericitic, surrounded by chlorite-epidote alteration. The presence of gold mineralization in the granodiorite and adjacent volcanic rocks is suggested from the results of silt, soil and rock-chip sampling.
In 1965, copper showings were found near Eureka Peak and staked as the En Group by Helicon Explorations Limited. In the same year, an electromagnetic survey was conducted on an east-facing talus slope near the base of Eureka Peak. A year later, two adits, totalling 32.7 metres, were drilled to provide a safe horizontal diamond-drill site. A 189-metre diamond-drill hole was completed shortly after but failed to reach the targeted zone.
During 1983 through 1992 Eureka Resources Inc. conducted extensive exploration programs on the area along with the nearby Frasergold (MINIFLE 093A 150) occurrence. In 1988, drilling is reported to have yielded 6.8 to 13.6 grams per tonne gold over 1 to 2 metres from the Eureka Peak area (Goodall, G., Campbell, K.V. (2007-01-29): Summary Report and Exploration Proposal on the Frasergold Project). In 1989, an inner "core" zone, measuring approximately 1829 by 1219 by 244 metres, was reported to grade from 0.13 to 0.44 per cent copper surrounded by an outer shell of about 0.10 per cent copper (EMR MR 223, 1989).
In 2018, Eureka Resources Inc. completed 1077 metres of drilling in three holes on the Nova zone in the FG Gold area. Drilling on the Nova zone intersected intervals of elevated gold and copper values over tens of metres, typically associated with one or more 1.5- to 2.0-metre intervals hosting 10 to 30 per cent pyrite yielding intercepts of up to 0.21 gram per tonne gold over 11.8 metres in hole DDH-18-001 and 0.59 gram per tonne gold with 0.14 per cent copper over 32.7 metres, including 1.52 grams per tonne gold and 0.15 per cent copper over 8.7 metres in hole DDH-18-002 (KORE Mining Ltd. [2020-12-16]: Technical Report on the South Cariboo Property, British Columbia, Canada). The drillholes were located near a small lake, approximately 1.2 kilometres west of the plotted location of the EN occurrence.
In 2019 and 2020, KORE Mining Ltd. completed programs of prospecting and geochemical (rock and soil) sampling on the area as part of the South Cariboo property. Rock samples from the Nova area are reported to have yielded up to 0.2 gram per tonne gold and 0.4 per cent copper (KORE Mining Ltd. [2020-12-16]: Technical Report on the South Cariboo Property, British Columbia, Canada).
For a complete exploration history of the area see the Frasergold (MINFILE 093A 150) occurrence.