Deposition and Transport of Gold by Thiosulphates, Veitsch, Austria

H. Kucha, W. Prohaska and E. F. Stumpfl
Institute of Geology and Mineral Deposits, Ave. Mickiewicza 30, 30-059 Kraków, Poland
Institute of Geological Sciences, Mining University, A-8700 Leoben, Austria

Abstract: Two types of gold can be distinguished in tetrahedrite from the Veitsch magnesite deposit, Austria. Primary gold present in unfractured massive tetrahedrite, has a grain size up to 18 μm and contains, on average, Cu 8.73, Ag 7.01, Au 78.63 and Hg 2.35 (wt.%). Secondary gold is present in fractures and is directly intergrown with digenite, covellite, Cu-thiosulphate, cuprite and chrysocolla but not with malachite or azurite. The secondary gold is up to 200 µm in size with an average composition of Cu 3.06, Ag 6.82, Au 86.41 and Hg 3.51 (wt.%). It is usually closely intergrown with thiosulphates containing up to 0.21 wt.% Au. This, together with the presence of ‘dirty’ gold with cloudy thiosulphate inclusions, directly indicates the transport and deposition of Au by a thiosulphate ligand. We believe this is the first reported direct evidence of gold transport and deposition by thiosulphate complexes in a natural environment.

Keywords: gold • tetrahedrite • magnesite • thiosulphate • gold transport and deposition • Veitsch deposit • Austria

Mineralogical Magazine; June 1995 v. 59; no. 395; p. 253-258; DOI: 10.1180/minmag.1995.059.395.09
© 1995, The Mineralogical Society
Mineralogical Society (