The GLOUCESTER showing is located on reverted Crown grant Lot 2809 which is approximately 1.7 kilometres north of the summit of Mount Franklin.
The showing occurs along a sheared contact between a limy quartzite of the Devonian-Triassic Harper Ranch Group and granodiorite of a unnamed Middle Jurassic intrusion. In the general area of the showing, the Harper Ranch Group also includes a cherty quartzite, argillite, altered tuff, and greenstone. Mineralization consists of chalcopyrite, sphalerite and molybdenite with pyrite and magnetite in a gangue of calcite, quartz, epidote and chlorite. The mineralization is best developed in a zone on the Harper Ranch side of the shear; little mineralization is noted in the granodiorite.
The GLOUCESTER was one of the earliest properties to be developed in the Franklin camp. By 1901, a 15-metre shaft had been sunk in "solid ore" and mineralization had been traced for about 120 metres on the surface. The GLOUCESTER claim was Crown granted as Lot 2809 to T.L. Merson and associates in 1902. In 1904, an adit was started about 35 metres lower in elevation than the shaft and by 1905 had been driven 60 metres toward the shaft. The shaft was reported to be 16.7 metres deep, although a later report suggests that the shaft may only be 10 metres deep.
In 1906, the GLOUCESTER was bonded to the Dominion Copper Co. Ltd. who extended the adit to 65 metres and then raised 28 metres from the end of the tunnel without striking any ore.
In 1920, the property was diamond-drilled by the Provincial Government under the Mineral Survey and Development Act. Eight holes, for an aggregate total of 880 metres, were drilled. The only mineralization encountered was small veinlets of pyrite with occasional segregations of hematite and specks of chalcopyrite. Drillholes drilled under the shaft and tunnel were barren of mineralization.
In 1964, Franklin Mines Ltd. acquired much of the Franklin camp, including the GLOUCESTER showing. The average of 2 samples from pits, representing 9 metres of chip sampling, assayed 0.05 grams per tonne platinum (Assessment Report 637). A magnetometer survey found anomalous readings only in the vicinity of the old workings.
In 1977, the GLOUCESTER showing was prospected by T.E. Lisle of the Hecla Mining Company. Nothing new of interest was found.
In 1982, Guy Allen prospected the GLOUCESTER and adjacent GH (082ENE006) showing. An inclined shaft, striking 242 degrees and dipping 62 degrees, was found on the property. A vein-filled shear, exposed in the wall of the shaft, strikes 257 degrees and dips 77 degrees to the north. The uppermost adit, 33 metres to the southwest of the shaft, was driven on a bearing of 290 degrees. A grab sample collected from the portal assayed 0.3 gram per tonne gold, 5.47 grams per tonne silver, 0.28 per cent copper, 0.038 per cent zinc and 0.023 per cent lead (Assessment Report 10953). Another adit is located 17 metres to the southeast of the shaft; it was driven into the steep hillside at 296 degrees intersecting the adit. The lowermost or main adit, located 42 metres to the east of the shaft, was driven at 290 degrees. No mineralization was noted near the portal or in the dump of the main adit.
In 1987, the GLOUCESTER showing was acquired by R. MacKillop and was examined by M.L. Malott. Observations of the workings confirm earlier reports. The mineralized contact between the granodiorite and the Harper Ranch quartzite strikes 240 degrees and dips 70 degrees to the southeast. Numerous pits and trenches were found on the mountainside above the upper adit. A sample from a pit 16 metres above the upper adit assayed 0.072 gram per tonne gold, 1.38 grams per tonne silver, 0.02 gram per tonne platinum and 0.108 per cent copper (Assessment Report 15467).