The Munster Basin is composed of Devonian terrestrial clastics with minor volcanics overlain by Carboniferous marine sandstones and shales with subordinate carbonates. Major folding and strike-slip faulting took place during the Variscan Orogeny. Vein-hosted Cu and barite are amongst a variety of mineral deposits worked in the past. The Devonian sequences are thought to contain potential palaeoplacer Au targets, while shale/carbonate-hosted Zn-Pb mineralization has recently been discovered in the Carboniferous strata.

The Longford-Down Massif is a geological zone that trends NE-SW from County Longford in the Republic of Ireland to County Down in Northern Ireland. The zone is bisected by the Orlock-Bridge Fault, splitting the region into two distinct stratigraphic units. To the north of the fault Ordovician argillaceous sediments dominate, whereas to the south Mid-Ordovician to early Silurian greywackes primarily composed of andesitic detritus dominate. Three principal groups of metallic mineral deposits occur in the Longford-Down inlier: Epigenetic vein deposits, mainly composed of Pb-Zn, but also including Sb-As-Au. A number of these vein deposits have been exploited historically. Stratiform manganiferous Fe-deposits of probable volcano-sedimentary origin. Several of these deposits were worked during the late-19th century. Minor porphyry copper type Cu-Mo mineralization associated with small granodiorite intrusions.