Tomnadashan Mine

Also within

Perth and Kinross County

Condition (NatureScot)

Habitats

Calaminarian grassland

Geology & landscape

Geological Feature: Cave / Cavern · Rock Type: Granite

Landscape processes: Karst, Volcanic / Igneous

Description

Tomnadashan Mine Tomnadashan Mine is located on the south side of Loch Tay, immediately south of the road beside the loch, 2 km south-west of Ardtalnaig. The site consists of an old mine and associated waste dumps, and it is important for its range of minerals and the lichens found on them. The mining took place over 100 years ago and was mainly for copper ore. There are very few old metal mines in Perth & Kinross, and Tomnadashan Mine supports the best example of metalliferous lichen communities in the district. The mineralisation occurs along the contact between two intrusives originally described as granite and lamprophyre, but more recently as lenses of granite and granodiorite in diorite. The diorite itself is sparsely mineralised with pyrite, but the more acid rocks are the main copper bearers and also contain calcite veinlets with molybdenite. Chalcopyrite and pyrite form irregular masses and pods along small fractures and along the granodiorite – diorite boundary. Fine disseminations of tetrahedrite are present and molybdenite is conspicuous in pyrite-rich areas. Rare bismuth minerals have also been identified. There is a large cavern-like excavation in which pockets of mineralisation can be seen and the dumps yield a rich and varied mineral assemblage including secondary as well as primary ore minerals. The site is not only an excellently exposed example of mineralisation associated with a small pluton or stock, but is also of considerable interest to the ore mineralogist. The old workings and the spoil heaps are of importance for their lichen community including a number of species restricted to heavy metal deposits. Most notably these include extensive stands of Rhizocarpon furfurosum which is abundantly fertile at this site, an unusual occurrence for this normally sterile species, together with nine further metalliferous lichen species.

Species mentioned

Plant communities