PGE-containing nickel-copper converter matte is blown to an iron-endpoint during Peirce-Smith conversion. The matte is granulated after conversion and the process can be described as fast cooling. The effect of changes in the iron-endpoint on matte mineralization during granulation or fast cooling is poorly understood. The aim of the study was to investigate the mineralogy and basic mineral chemistry of PGE-containing nickel converter matte as a function of iron-endpoints 5.17 wt%, 0.99 wt% and 0.15 wt%. A combination of mineralogical analytical techniques was applied to methodically characterise the converter matte. Representative sub-samples for the respective iron-endpoints were characterised using quantitative X-ray diffractometry (QXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution scanning transmission electron microscopy (HRSTEM) and bulk chemical and instrumentation methods. Moreover, solidification paths were created for the respective iron-endpoints to use as an assistant tool in understanding matte mineralogy. The matte mineralogy for iron-endpoint 5.17 wt% is characteristic of a significantly higher heazlewoodite relative abundance (77.89%) in comparison with that for iron-endpoints 0.99 wt% (62.92%) and 0.15 wt% (63.67%). Iron-endpoints 0.99 wt% and 0.15 wt% are in contrast, characteristic of a higher chalcocite relative abundance (18.56% and 17.86% respectively) in comparison with 12.04% for the high iron-endpoint. The lower iron-endpoints are further characteristic of a significantly higher alloy relative abundance in comparison with the high iron-endpoint. The PGE-containing nickel-dominant alloy phase for the high iron-endpoint is extremely fine grained, set in the heazlewoodite matrix and characteristic of the exsolution origin. The NiCu-dominant, PGE-containing alloy phases for iron-endpoints 0.99 wt% and 0.15 wt% are characterised by an exsolution origin followed by exsolution modifications probably due to PGE saturation at an early cumulus stage and the presence of other elements. (C) 2010 Elsevier Ltd. All rights reserved.