Note: Following description is from Mindat. For the avoidance of doubt, mineral collecting in the Caldbeck Fells is only allowable under license, which are granted for specific zones.

The workings at the head of Potts Gill began around 1870, focusing on the outcrop of prominent east-west veins in search of lead. However, very little lead ore was discovered in these veins, which were primarily filled with barite. Despite this, barite mining commenced with the outbreak of World War I and continued until the mine’s closure in 1947. The barite extracted was mostly massive, and only a small amount of specimen-quality material was found.

Of particular interest are reports of rare copper and lead minerals found in the dumps of the ‘Old No. 1 level’ workings, as documented by Kingsbury and Hartley in the 1950s. These minerals, including vanadinite and various rare supergene copper minerals, may have originated from crosscutting copper veins encountered during the barite mining. However, there is no detailed record of the source in situ, and the origin of Kingsbury’s specimens remains speculative.

It’s worth noting that Kingsbury’s credibility has been called into question, as he has been shown to have falsified occurrences in the past. Nevertheless, the suite of minerals reported by Kingsbury and Hartley, including chalcophyllite, conichalcite, devilline, dioptase, serpierite, and tyrolite, is considered unique in the district. While subsequent collectors have found cornwallite, the other rare minerals have not been rediscovered. Additionally, Cooper and Stanley (1990) mention that the newly described species philipsburgite was identified in material collected over 20 years prior.