In accordance with its goal to help maintain an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines is developing a method to recover nickel, cobalt, and copper from low-grade domestic laterites. The metals are recovered by a system that incorporates selective reduction and a controlled oxidizing ammonia-ammonium sulfate leach with solvent extraction and electrowinning. To gain a better understanding of the true nature of the products reduced and leached with the system, the Bureau engaged in a joint study with the Denver Research Institute. In this study scanning electron microscopy, electron microbeam analysis, x-ray diffractometry, petrography, and standard chemical analysis techniques were used to determine the association of nickel with other elements in the laterite under various reduction conditions and in the leached product. The study revealed that alumina and magnesia influence the formation of refractory nickel compounds, and that sulfur tends to prevent the formation of these compounds.