Foss Mine, Aberfeldy, Perth and Kinross, Scotland, UKi

Regional Level Types
Foss Mine	Mine
Aberfeldy	Town
Perth and Kinross	Council Area
Scotland	Country
UK	Country

Baryte deposit in Dalradian schist and quartzite.

Foss subdivided into Foss West (where barite was mined) and Foss East (not exploited). The deposits were discovered in the late 1970s by the British Geological Survey, then named the Institute of Geological Sciences. Barite production at the Foss Mine and adjacent Open Pits commenced in the early 1980s, and in recent years about 40,000 metric tons of barite rock has been extracted annually by M-I SWACO, a Schlumberger company. Before closure in 2021, Foss Mine produced over 1 million tons with a similar resource remaining at depth in a structurally complex, folded, and stretched orebody.
These features suggest rapid deposition of the barite during hydrothermal exhalative episodes that were vigorous but short-lived and episodic. Seven such episodes are represented in the Foss deposit (labeled M1 to M7). In Foss West, two mineralized beds outcrop near the stratigraphic top of the Ben Eagach Schist formation. The uppermost (M5) is more extensive and was worked for barite in Foss Mine, whereas barite worked in the Open Pits belongs to both M3 and M5 beds. In Foss East, thick barite (up to 25 m true thickness) in the vicinity of the Frenich Burn comprises a composite bed of M3 to M7 inclusive, which splits at depth and along strike eastwards into discrete mineralized beds separated by wedges of metasediment. Toward the eastern extremity of the Foss deposit, the same mineralized beds become widely separated within a package of sedimentary strata up to 100 m in thickness.

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References