Iron-bearing particles in two Athabasca oil sands ore samples have been characterized in this study by electron microscopy. One sample was taken from a "good processing ore" and one from a "poor processing ore". These samples were subjected to a batch extraction process and the resulting solids in the primary froth were characterized. While iron-bearing minerals such as magnetite and hematite were common in both ore samples, pyrite and goethite were only found in the poor processing ore and wustite was identified only in the good processing ore. The iron-bearing particles were concentrated in the primary froth stream from batch extraction, and their sizes varied from a few nanometers to several hundred nanometers. The nanometer scale iron bearing minerals have been identified in two different arrangements. Nanoscale iron-bearing minerals either form patches on top of relatively large (200-300 nm) clay particles, or they combine with nanoscale clay and toluene insoluble organic material to form mineral-organic aggregates.