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The Hyrkkölä Native Copper Mineralization: a Natural Analogue for Copper Canisters

Published online by Cambridge University Press:  03 September 2012

Nuria Marcos Perea
Nuria Marcos Perea*
Affiliation:
Helsinki University of Technology, Engineering Geology & Geophysics Lab, FIN-02150 Espoo, FINLAND
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Abstract

The Hyrkkölä U-Cu mineralization is located in south-western Finland, near the Palmottu analog site, in crystalline, metamorphic bedrock. The age of the mineralization is estimated to be between 1.8 and 1.7 Ga. The existence of native copper and copper sulfides in open fractures in the near-surface zone allows us to study the native copper corrosion process in conditions analogous to a nuclear fuel waste repository.

From the study of mineral assemblages or paragenesis, it appears that the formation of copper sulfide (djurleite, Cu1.934S) after native copper (Cu°) under anoxic (reducing) conditions is enhanced by the availability of dissolved hydrogen sulfide (HS) in the groundwater circulating in open fractures in the near-surface zone. The minimum concentration of HS in the groundwater is estimated to be of the order of 10-5 M (∼ 10-4 g/1) and the minimum pH value not lower than about 7.8 as indicated by the presence of calcite crystals in the same fracture.

The present study is the first one performed on occurrences of native copper in reducing, neutral to slightly alkaline groundwaters. Thus, the data obtained is of most relevance in improving models of anoxic corrosion of copper canisters.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 1153
Copyright
Copyright © Materials Research Society 1997

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References

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