Abstract Introduction The base metal and barite deposits of the Silvermines district occur on the northern flank of the Silvermines Mountains, some 8km south of the market town of Nenagh in northern County Tipperary. The earliest records of mining in the area date back to the early 9th century when argentiferous galena was mined by the Danes. From the 16th to the 19th century subsequent operations along the Silvermines Fault raised copper, silver, lead, zinc and sulfur ores. In this century, mining of calamine (smithsonite) at Ballygowan South and lead at Shallee continued sporadically until 1958. The major base metal and barite deposits were discovered in 1962 by geologically directed diamond drilling, and worked until July 1982 by Mogul of Ireland Ltd., and until September 1993 by Magcobar Ltd. (Dresser Industries) respectively. The Mogul mine produced some 10.8Mt of ore grading 2.70% Pb and 7.36% Zn from 1968 until closure, from underground workings on the Upper G, Lower G, B and K Zones (Table 1; also see page 246). The Magcobar operation produced approximately 4.6Mt of 85% BaS0 4 lump barite. Currently (1994) the Silvermines area is being explored by Ennex International Pic in joint venture with Rayrock Yellowknife Resources Limited who hope to add to the known remaining base-metal ore reserves of 6,894 929t grading 2.26% Pb and 4.98% Zn.