Mineralogical controls on storage of As, Cu, Pb and Zn at the abandoned Mathiatis massive sulphide mine, Cyprus

Abstract

AbstractThe Mathiatis massive sulphide deposit in Cyprus was a low-grade (0.3% Cu), three million ton ore body of pyrite and minor chalcopyrite occurring within basaltic lavas of the Troodos ophiolite. Cessation of mining in 1987 left a deep open pit surrounded by large heaps of spoil, which are undergoing oxidation and leaching. The aim of this study was to determine the mineralogical controls on the storage and potential remobilization of As, Cu, Pb and Zn within, and from, mine spoil heaps. Most of the spoil samples collected, and related materials (stream sediment, reaction zone between a boulder of massive pyrite and calcareous chert, salt crusts on stream beds), are enriched in As (27—220 ppm), Cu (110—400 ppm), Pb (10—140 ppm) and Zn (290—12,000 ppm) relative to both the basalt and calcareous chert (As 4—10 ppm, Cu 20—76 ppm, Pb 3—6 ppm, Zn 39—200 ppm).Arsenic, Cu, Pb and Zn in the spoil and related materials are associated with Fe(-Al-S)-O, Fe(-Al-Mg)-S-O, Al(-Mg-Fe)-S-O and Mg(-Al-Fe)-S-O phases (the brackets represent minor components of less than 20 wt.% within the phases). Chemical extraction work using CaCl2 suggests that Cu, Zn and to some extent, As, are potentially more soluble than Pb. This is corroborated by the very high total concentrations of Cu and Zn in both the secondary salt crusts and the reaction zone material, high CaCl2-extractable As, Cu and Zn in the salt crusts, and aqueous data for the Mathiatis mine area collected for a European Union LIFE report. This may have implications for ecosystem health and water quality in the Mathiatis area and areas of similar mineralogy and climate world wide.