Figs. 1-2: Left: Coarse, vuggy milky quartz, voids coated with orange limonite and lesser, granular, fine-grained, pale yellow pyromorphite. From the Old Luganure mine, Glendasan, county Wicklow, Ireland. The adjacent valleys of Glendalough and Glendasan are in the uplands of central Wicklow, west of Wicklow and northwest of Rathdrum. The area, as the crow flies, is just 35 km south of Dublin. Veins here run mostly north-south, and excavations started as long ago as 1800. The Old Luganure mine and its neighbours worked the Ruplagh lode (Cole, 1922, pp.109-110). The old mines are now in the Wicklow Mountains National Park, and were mined extensively for lead (as well as silver, and later zinc) in the 19th and 20th centuries. See links in reference list to the Glens of Lead and Wicklow Mountains National Park web sites. Paleozoic sediments in the region are cut by the S-type granitoid rocks of the Leinster batholith, the largest Caledonian intrusion in the British Isles. The 1500 km² batholith consists of five domed plutons, and has been dated at around 405 Ma (Stillman, 2001, pp.164-169). There is strong shear zone development along the border between host metasediments and the Leinster granite (Reavy, 2013, pp.300-302). Numerous veins along the contact of granite and host mica schist supported the mining industry. The veins "seem thus to be intimately connected with the final stages of the consolidation of the granite" (Cole, 1922, p.109), an association deduced earlier by W. Warington Smyth in 1853 (ibid., p.109).

Right: Pyromorphite, as a coating of beautiful green sub-mm crystals on a pale, greyish-white matrix of vuggy silica. From the Susanna mine, Leadhills district, Scotland (a locality that has also produced yellow pyromorphite). Some 70 veins were worked in an area of just 8 km², around the adjacent villages of Leadhills and Wanlockhead, in the Lowther Hills of the Southern Uplands of southwest Scotland. Though there was early interest in gold, lead mining rose rapidly in importance in the second half of the 18th century (Gillanders, 1981). Galena was the primary lead ore mineral but an interesting range of secondary minerals (of copper, zinc and lead) developed later. Over 60 mineral species are known from the district, where mineralization was confined to host units of greywacke and mudstone. Pyromorphite is found on most of the local mine dumps, but unusual orange and red varieties of pyromorphite were reported only in the Susanna mine (Gillanders, 1981, quoting the great Scottish mineralogist M.F. Heddle, author of the 1901 classic The Mineralogy of Scotland).

Samples shown here are from David Joyce (specimens 14607 and 28979; the latter formerly P091471 of the Tony Steede collection), 2022.