MINERALOGICAL AND GEOCHEMICAL SIGNATURE OF MINE WASTE CONTAMINATION, TRESILLIAN RIVER, FAL ESTUARY, CORNWALL, UK

The mineralized district of SW England was one of the world's greatest mining areas, with mining commencing in the Bronze age, peaking in th e 1850s to 1890s, but still continuing to the present day. Consequentl y, it is not surprising that mining has had a major impact on the envi ronmental geochemistry of SW England. In this study, the mineralogical and geochemical signature of mine waste contamination within the Fal Estuary at Tresillian, Cornwall, has been examined. A pulse of mine wa ste contamination is recognized at approximately 50 cm below present d ay sediment surface. Sn, As, Cu, Pb, and Zn are all enriched within th is contaminated interval with up to 1800 mg kg(-1) Sn, 290 mg kg(-1) A s, 508 mg kg(-1) Pb, 2210 mg kg(-1) Zn, and 1380 mg kg(-1) Cu. Within this interval, the dominant minerals present include chalcopyrite, ars enopyrite, pyrite, cassiterite, Fe-Ti oxides (ilmenite and ?rutile), w olframite, sphalerite, baryte, zircon, monazite, tourmaline and xenoti me. In addition, man-made slag products commonly occur. The exact timi ng of the release of mine waste into the estuary is poorly constrained , but probably occurred during or immediately following the peak in mi ning activity in the nearby Camborne-Redruth district, which was betwe en 1853 and 1893. The mine waste may have entered the estuary either v ia the Tresillian River and its tributaries or via Calenick Creek and the Truro River and/or the Carnon River which flows into Rostronguet C reek.