Northern Norrbotten County is one of the three major ore producing districts in Sweden. Based on the predominance of epigenetic Cu-Au and Fe-oxide mineralization this region is regarded as a typical IOCG province. The massive to layered Viscaria Cu-deposit is proposed to be a VMS deposit of Besshi-type and is unique in deposit type of the region. The volcaniclastic rocks of the Viscaria Formation hosting the Viscaria deposit belong to the rift related Kiruna Greenstone Group. The Viscaria deposit consists of three stratiform-stratabound mineralized zones: A-, B- and D-zone. Sulphide mineralization of the D-zone differs in structural features, host rock, mineralization style and Fe-oxide dominance over Cu-sulphides compared to the main Cu-ore in the A-zone. These differences between A- and D-zone mineralization styles raise the subject that the D-zone could be of a different origin.   The Kiruna area is mainly covered by glacial-till, which contributes to limited bedrock exposure. This becomes a challenge when exploring for new deposits and highlights the importance of good geological knowledge obtained from existing deposits to carry through successful exploration programs. The objective of this study is to characterize the Fe-Cu-occurrence and the associated alteration halo of the Viscaria D-zone. Alteration halos can reach several kilometres away from the main ore zone and provides mineralogical and chemical signatures that extend the target area significantly in exploration for new deposits. Detailed core logging, optical microscopic studies, lithogeochemistry and electron microprobe analyses was utilized to contribute to a better genetic understanding of the D-zone and the associated hanging wall and footwall alteration features. The study shows that the main ore minerals of the D-zone consist of magnetite and chalcopyrite, and minor pyrite and hematite. The major alteration minerals associated with mineralization are calcite, actinolite/tremolite, epidote, chlorite and also biotite and scapolite in the hanging wall. The most prominent potential ore vector is calcite veins and biotite, as the abundance increase towards the D-zone. D-zone are further characterised by low REE concentrations, similarly to the calcic-dolomite host. The study also shows that the alteration halo of the D-zone is different in the hanging wall compared to the footwall, which is confirmed by the lithogeochemistry and mineral chemistry. The footwall is characterized by spilitization and chlorite alteration. The lithogeochemistry of the D-zone and the hanging wall reveals element mobility of Mg, Ba, Fe, Na, K, Cu and Zn. Mineral chemistry of epidote, amphibole and chlorite shows chemical changes in Fe/Al- and Mg/Fe-ratios. According to the result of this thesis and earlier studies, the D-zone mineralization is suggested to be part of the VMS system forming the stratigraphically above laying A-zone of the Viscaria Cu-deposit.

Ammonium has been detected in and around several epithermal Au-Ag deposits, including those in Nevada, Japan, Argentina, Mexico, and New Zealand, using short-wave infrared (SWIR) reflectance spectroscopy. This study examined the distribution and occurrence of ammonium in three epithermal low-sulfidation vein-type deposits in the Hauraki goldfield of New Zealand: Martha (>6.7Moz Au, >42.1Moz Ag), Favona (>0.6Moz Au, >2.36Moz Ag), and the recently discovered Wharekirauponga (WKP; 0.42Moz Au, 0.8Moz Ag) deposit. The Martha and Favona auriferous quartz-adularia veins are hosted by late Miocene to Pliocene andesite, whereas auriferous veins at WKP are hosted by late Miocene to Pliocene rhyolite. The wallrock of all three deposits is altered to form quartz, illite, smectite, adularia, chlorite, and pyrite +/- kaolinite. Ammonium contents are enriched (>137 ppm) in wallrock samples from all three deposits and low (<94 ppm) in vein samples. Ammonium contents are higher at Favona (<10,675 ppm) than at Martha (<192 ppm) and WKP (<2,783 ppm). Leaching experiments using a 2N KCl solution show that most ammonium is in mineral structures (>90% at Favona, >80% at Martha, >70% at WKP). There is a positive correlation of ammonium contents with LOI (0.6 – 16.3 wt%) and with K2O (1.3 – 8.0 wt%) in all samples which suggest a hydrous potassium mineral as the major host of the ammonium. This is supported by the SWIR data obtained by previous workers of these samples where they show an absorption at ~1410 nm due to OH. At Favona, samples with high ammonium (>990 ppm) are reported to have significant absorption at ~2000 nm and ~2100 nm in the SWIR spectra likely due to ammonium. High ammonium contents (990 – 10,675 ppm) are found in rocks less than ~100m from the Favona vein which occur within an ammonium-bearing zone identified by previous workers based on SWIR. Samples outside of this zone contain low ammonium (107 – 301 ppm) with the smectite altered samples being the lowest. Ammonium contents within the hangingwall (1,827 – 10,675 ppm) of the Favona vein tend to be higher than in the footwall (990 – 4,301 ppm) and are highest within the most intensely illite altered rocks. At WKP, the intensely adularia +/- minor illite altered samples within 100m of the main East-Graben (EG) vein contain low ammonium (<200 ppm). The intensely illite altered samples away from the EG vein (>100m) have higher ammonium contents (200 – 800 ppm). This relationship of high ammonium contents to high illite abundance confirms illite as the major host of ammonium in these deposits. δ15N values for all samples (n=54) including near and far from auriferous veins range from +0.5 to +7.9 ‰, suggesting the derivation of most of the ammonium from the Jurassic greywacke basement or sediments intercalated within the volcanic rocks.