PRELIMINARY DATA SHOWING GEOCHEMICAL CHARACTERISTICS AND RELATIONSHIPS AMONG AURIFEROUS PYRITE FROM VARYING ORE UNITS AT ROUND MOUNTAIN GOLD MINE

Round Mountain Gold Mine is a low-sulfidation gold deposit in Nevada characterized by native gold and auriferous pyrite. Formed 26 myr ago through intrusion of hydrothermal fluids, the deposit is one of Kinross Gold’s biggest producers in North America and a characteristic example of low-sulfidation type epithermal gold deposits. Understanding geochemical relationships among auriferous pyrite from different ore units is crucial to properly evaluate the history of the ore deposit. As such, pyrite grains from three different ore units are being extensively studied with laser ablation- inductively coupled plasma -mass spectrometry (LA-ICP-MS) and secondary ion mass spectrometry (SIMS) in order to elucidate geochemical and isotopic relationships in and among pyrite grains.

Pyrite grains were taken from three stratigraphically sequential ores, two ash-flow tuff units and one meta-sedimentary unit that each constitute major gold sources. Based on peer reviewed research for Round Mountain and other similar deposits, we expect to see a positive correlation between Au and As ± Sb, Cu and Te. In addition, given the known relationship between epithermal deposits and intrusive igneous bodies, we posit that Au-rich domains in pyrite will correspond to relatively lower ³⁴S/³²S indicating a magmatic origin for ore forming fluids. Spatial distribution of trace and minor elements as well as S isotopes in pyrite will also allow us to determine the sequence of ore mineralization and investigate possible pyrite transport between ore units. This research serves to advance our understanding of ore deposit geology and provide the scientific backing for improvement of gold recovery at the mine.