The Joh 4 occurrence, near the northwest corner of the Joh 4 claim, is located about 1.7 kilometres east of Darb Lake and approximately 173 kilometres north-northeast of the community of South Hazelton (Assessment Report 21782).
Regionally, the area is underlain by Upper Triassic Jurassic Takla Group volcanic rocks. A porphyritic hornblende monzonite stock of the Early Jurassic Hogem batholith intrudes the volcanics northeast of Johanson Lake. Recent mapping to the south has redefined the Hogem batholith as part Intrusive Complex (Open File 1992-11).
The areas of the Joh showings (Joh 1, 094D 168; Joh 2, 094D 167; Joh 4, this description; Joh 7, 094D 179) are underlain by Takla Group volcanic rocks and possibly coeval Late Triassic intrusions. These comprise porphyritic andesite, banded tuff and volcanic sandstone intruded to the northwest and southeast of Darb Lake by diorite to monzonite stocks. Diorite plugs, locally chloritized and carbonatized, commonly average 3 to 4 per cent disseminated pyrite. The volcanics are hornfelsed and contain bands of amphibolite within 300 metres of the intrusive contact.
Mineralization was discovered in three main areas on the Joh property, which correspond to large magnetic highs and an intrusive-volcanic contact zone.
The Joh 4 showing area is underlain by porphyritic andesite flows and tuffs intruded by monzonite-diorite stocks and granite-granodiorite of the Hogem batholith. The showing consists of disseminated chalcopyrite in diorite and in epidote-K-feldspar stringer zones. The mineralization occurs in a diorite-volcanic contact zone. Fourteen rock samples taken from this showing assayed greater than 0.1 per cent copper and fourteen samples assayed greater than 0.2 gram per tonne gold (Assessment Report 21782).
In the early 1970s, the Red Lion area was explored by the UMEX-Wenner Gren Joint Venture. Their work consisted of stream sediment sampling and an aeromagnetic survey that covered the Red Lion property but was part of a much larger survey. Copper stream sediment anomalies were identified at Red Lion, associated with aeromagnetic anomalies that correlate with three plutons intruding Takla Group volcanic strata. Copper mineralization was reported in a diorite intrusion west of Darb Lake and in diorite and volcanic rocks to the southeast of Darb Lake.
In 1991, Swannell Minerals Corporation acquired an option on a property that encompassed the central part of Red Lion and undertook stream sediment geochemistry and prospecting with encouraging results. This was followed up in 1992 by 97 kilometres of grid lines, geological mapping and rock and soil sampling, producing 109 and 848 samples respectively, primarily on the ridge to the southeast of Darb Lake. This work outlined a strong, 4500 by 700 metres copper-gold soil anomaly, associated with porphyry-style copper-gold showings, at the contact of propylitized monzodiorite and andesite. Limited ground magnetometer work was done, with conclusive results, but apparently no induced polarization (IP) surveying or drill testing was done. In 1994, Hemlo Gold Mines Inc. sampled a small grid over a part of the area gridded by Swannell to the southeast of Darb Lake and duplicated the copper-gold soil anomaly. Rock sampling was conducted in the area of the anomaly and returned some anomalous copper and gold values. However, although dioritic intrusions and structural deformation were observed in the mineralized areas, it was of the opinion that there was no evidence of continuous surface mineralization or alteration that would be expected with a large-scale porphyry or skarn-related system. Hemlo did no further work.
In 2004-05, Serengeti Resources Inc. carried out limited stream sediment and rock sampling in the central part of the Red Lion area and confirmed some of the copper and gold anomalies from previous work. Additional rock sampling and geological work were recommended, but not carried out.
In 2011, DeCoors Mining Corp. undertook mobile metal ion (MMI) soil geochemical sampling over a small grid on the central part of their extensive Darby property, in addition to limited rock sampling, that were part of a larger-scale program that covered portions of the Red Lion property. Rock sampling occurred about 800 to 1800 metres to the northwest of the Darb occurrence, around Joh 4 (094D 165) and just southeast of Joh 2 (094D 167). Assessment Report 32618 (2011) presents geochemical results for the samples and a brief evaluation of the results from the Red Lion area. Aster imaging techniques were also used to prepare maps for the Darby property on behalf of DeCoors Mining Ltd. representing areas of siliceous rocks, sericite and illite, alunite and/or kaolinite, and iron oxides (Assessment Report 32364).
In 2014, on behalf of Garibaldi Resources Corp., an interpretation of satellite imagery in the Red Lion property area, as well as a compilation of all available exploration data, was completed to determine the most favourable locations to focus exploration work. Lineaments were plotted on a georeferenced satellite image to identify common trends for structures that may have provided controls to mineralization. The identified lineament trends have predominant north-northwest (NNW) and northeast (NE) orientations which correspond to field observations of common joint and shear trends. Many of the reported mineral occurrences, as well as mafic dikes, are commonly hosted by structures with NNW orientations, suggesting that lineaments may provide important indications for focusing exploration.
In 2015-16, a work program on behalf of Garibaldi Resources Corp. was completed on their large Red Lion property which covers the Joh 1, 2, 4, and 7 showings (094D 168, 167, 165, 179). The work comprised an airborne magnetic and radiometric survey (545 line-kilometres), a wide-spaced induced polarization survey (26.4 line-kilometres), and a brief geological and geochemical program to evaluate parts of the induced polarization chargeability anomalies.
In 2018, an exploration program was conducted by Garibaldi Resources on the Red Lion project. In total 461 soil samples and 51 rock samples were taken at various sites within the western portion of the property (RL West). The area of soil sampling was bound on the east by the west shore of Darb Lake. See Joh 1 (094D 168) and Joh 3 (094D 169).
