'Invisible' gold SIMS results from sulphides and arsenides of selected Finnish Au deposits

摘要

Samples of eleven Finnish gold prospects were analysed with Secondary Ion Mass Spectrometry (SIMS) to determine the mode of occurrence of Au. In sulfides and arsenides gold occurs as solid solution and colloidal size (200A-0.2μm) microinclusions in arsenopyrite-loellingite as well as visible micron size native gold inclusions. The solid solution gold contents in arsenopyrite were up to 2700 ppm, in arsenic-bearing pyrite < 0.2 to 260 ppm, in loellingite from <0.2 to 33 ppm, in pyrrhotine 0.47 to 1.6 ppm and in chalcopyrite 0.18-0.52 ppm. The telluride-pyrite -gold prospects had only 0.19-2.00 ppm lattice bound gold in pyrite.