The Jeno occurrence is situated in the Duckling Creek area of the Swannell Ranges (Omineca Mountains), approximately 2.5 kilometres south-southeast of the Lorraine occurrence (093N 002) and 59 kilometres northeast of Takla Landing.
The area is underlain by mesozonal plutonic rocks assigned to the Late Triassic to Early Cretaceous Hogem Intrusive Complex which have been emplaced into volcanic rocks of the Middle Triassic to Lower Jurassic Takla Group, east of the Pinchi fault zone. The plutonic rocks form an elongate batholith, extending from Chuchi Lake north to the Mesilinka River. The structural setting of the batholith and the intruded Takla Group is one of vertical tectonics associated with graben development (Bulletin 70).
In the immediate area of the showing, medium-grained, strongly foliated, mafic syenite is in contact with light grey coloured megacrystic syenite comprising up to 8 centimetres long, variably foliated potassium feldspar phenocrysts in a medium-grained groundmass. These rocks likely belong to the Middle Jurassic Duckling Creek Syenite Complex, one phase of the Hogem Intrusive Complex.
Reports (ca. 1949) describe the showing as comprising chalcopyrite, bornite and malachite hosted by fine-grained pink syenite or monzonite exposed in a northwest trending outcrop 30 metres long by up to 8 metres wide. A chip sample across 2.1 metres reportedly assayed 3.24 per cent copper (Assessment Report 21992, page 10).
Reports describe copper-rich pods up to 15 centimetres thick occurring in a vertically dipping east-west fracture near the contact of the mafic and megacrystic syenite units. The pods contain semi-massive bornite, lesser chalcopyrite and abundant malachite stains and appear to be restricted to a 10 to 15 metre strike length. One grab sample from the outcrop assayed 14.4 grams per tonne gold, 276 grams per tonne silver, 1.865 grams per tonne palladium and nearly 10 per cent copper (Assessment Report 21992, page 21). Better results were obtained from local float samples. Values of up to 0.58 gram per tonne platinum are reported from bornite-rich breccia (www.eastfield/group.com).
The BM (Jeno) zone was explored by Lysander Minerals Corp. in 1999 as part of the Jajay property which includes the Lorraine (093N 002). Eastfield Resources Ltd. optioned the Jajay in late 2000. Refer to Lorraine (093N 002) for a detailed work history of the area.
Petrographic studies indicate that garnet and pyroxene with interstitial bornite and exsolved chalcopyrite, as well as fresh biotite clinopyroxenite with interstitial sulphides (bornite and chalcopyrite), magnetite and apatite both suggests an orthomagmatic origin for the sulphides. One sample, not located, is said to carry 19 grams per tonne gold, 580 parts per billion platinum, and 3460 parts per billion palladium (Geofile 2002-2).
In 2010, Teck Resources Limited conducted a spectral and lithogeochemical sampling of historic drill core and soil sampling program on the Too Good and Bishop zones of the Lorraine-Jajay property. Soils were sampled for pH and copper, molybdenum, zinc, lead and gold with anomalous geochemical results within both sampled zones.
