Irish-type Zn-Pb deposits in the context of global zinc supply

Abstract

Zinc is the fourth most consumed metal globally and its corrosion resistance properties contribute significantly to the longevity, reliability, and sustainability of construction and infrastructure projects, vehicle manufacturing, and green technologies. By extending the lifespan of these assets and promoting durability, zinc supports the goals of the green transition by reducing resource consumption, minimizing waste, and enhancing overall environmental performance. Four broad ore deposit types account for over 90% of global zinc production and known resources. These are, in order of importance, shale-hosted massive sulphide (‘VHMS’) deposits, volcanogenic massive sulphide (‘VMS’) deposits, carbonate replacement (‘CRD’) deposits, and Irish-type / Mississippi-valley type (‘IT’ / ‘MVT’) deposits. Each ore deposit type contains a relatively small number of world-class ore deposits which are characterized by their large size, high-grades, and economic viability. These world class deposits represent the most significant de-posits within their respective deposit types and generally attract substantial attention and investment from mining and exploration companies. The Irish Midlands basin is a globally significant area for zinc exploration and mining and discoveries over the past 60 years have demonstrated its potential to generate world-class deposits. One notable example is the Navan de-posit, which is one of the largest known Irish-Type/Mississippi Valley-Type (IT / MVT) deposits in the world. Navan has been a prolific producer of zinc and lead ores for the past 45 years, contributing significantly to the mineral wealth and economic development of the region. Irish-type deposits, such as Navan and Lisheen/Galmoy, have the advantage of being metallurgically straightforward and of producing clean concentrates with minimal impurities. Such clean concentrates are highly sought after by zinc smelters worldwide, as they allow for efficient blending with other zinc concentrates of lower quality. After decades of mineral exploration, the potential for new discoveries in the Irish Midlands basin still remains high. The metal endowment of the basin and quality of its deposits, coupled with advances in exploration technologies, such as seismics, make it an attractive exploration play. Large areas of the basin also remain relatively underexplored, particularly under cover rock sequences, such as the Tober Colleen Formation (the lowermost part of the “Calp”). Indeed, the combination of accumulated geological knowledge, technological advancements, and on-going exploration programmes greatly enhances the likelihood of new and exciting mineral discoveries in the Irish Midlands basin in the coming years. In summary, the Irish Midlands basin's track record of discoveries and the characteristics of Irish-type deposits, including their size, grade and concentrate quality, reinforce the basin's significance in global zinc exploration and mining. Production of zinc from the Irish Midlands basin also contributes to the European Union’s (EU) mineral self-sufficiency objectives and sustainability agenda thereby enhancing resource security, reducing carbon emissions, and fostering a more sustainable and resilient mineral supply chain within the EU.