Lead-Antimony Mineralization at Bwlch Mine, Deganwy, Wales

Abstract

Gwynedd, is one of the lesser known localities in the British Isles for lead sulphantimonide minerals, and recent work by the authors has identified a wider range of these than previously reported. All of the samples referred to in this paper are lodged in the mineral collection in the Department of Geology, National Museum of Wales, under accession numbers NMW 82.1G., NMW 83.44G. and NMW 85.70G. Location and geological setting Bwlch Mine (SH 7870 7944) is located some 200 m NW of Bwlch. Little is known of the early history of the mine, but it received a brief mention by Russell (1944) who investigated specimens of stibnite he had discovered in the collections of the Museum of Practical Geology and of the Royal Geological Society of Cornwall. During this work he also established the presence of semseyite and jamesonite. It was while attempting to verify these latter minerals that the present study developed. The mine is driven into a small hill composed of highly altered, nodular ignimbrite of Caradoc (Ordovician) age, belonging to the Capel Curig Volcanic Formation (M. J. C. Nutt, pers. comm., 1986). At present there is no access to previouslyworked levels and material can only be collected from a small overgrown waste dump. At Bwlch Mine the antimony minerals occur typically in irregular patches, and in thin veins and stringers up to 2 cm (but more usually of the order

On Irish bacteriometallogenesis and its wider connotations

“…It is notable that the veins of more variable trend are those developed south of the Iapetus Suture. Indeed, once we are as far south as the extensive Central Wales lead-zinc-silver district and the West Shropshire Orefield in England, most of the richer veins run EN-E, and N-S veins are absent (Jones 1922;Dines, 1958;Hughes, 1959;Fletcher et al, 1993;Bevins et al, 2010;Wilson et al, 2016;cf. the Rathdowney trend in Ireland: Torremans et al, 2018;Turner et al, 2019).…”