Pyrrhotite Horizons of the Pyhasalmi District, Central Finland

: Laitala J

: Andre-Mayer, AS; Cathelineau, M; Muchez, P; Pirard, E; Sindern, S

: SGA Biennial Meeting on Mineral Resources in a Sustainable World

: 2015

: 2015 NANCY: MINERAL RESOURCES IN A SUSTAINABLE WORLD, VOLS 1-5

: MINERAL RESOURCES IN A SUSTAINABLE WORLD, VOLS 1-5

: AUG 24-27, 2015

: 2067

: 2070

: 4

: 978-2-85555-066-4

The Vihanti-Pyhasalmi district is a mature volcanogenic massive sulphide (VMS) mining camp in central Finland. Exploration in the Pyhasalmi area has often led to discovery of barren pyrrhotite mineralisation. The pyrrhotite occurrences are laterally extensive and, therefore, called as "pyrrhotite horizons". To get better understanding from their nature and genesis, pyrrhotite horizons from four different locations were selected for a detailed study. Careful logging of drill core, optical mineralogy, whole-rock geochemical data, and electron probe microanalyser (EPMA) and sulphur isotope analyses were the main research methods. Initial working hypothesis, where the pyrrhotite horizons were regarded as metalliferous chemical sediments, seems to be correct. The pyrrhotite horizons show many features indicating a sedimentary origin: They are laterally extensive, have early laminated features and compositional variation, have negative delta S-34 values that are typical for the sedimentary sulphur, show slight enrichment in redox-sensitive elements, and are strongly enriched in Fe and variably in Ni, Cu and Zn.