In a recent study, we discovered that oxygen from the gas phase, organic portions of the coal, and minerals in the coal have profound influence on the formation and desorption of stable surface oxides in the early stages of coal combustion. In an attempt to isolate the effects of minerals, demineralized coals (DMC) are oxidized in O-2 with a contact time less than 1 s, and the amount and strength of stable surface oxides are characterized by temperature-programmed desorption (TPD) up to 1650 degrees C. Young chars derived from both demineralized lignite and bituminous coals show low and flat TPD profiles over a wide temperature range, signifying the minerals' catalytic activities in forming stable surface oxides for both coals. Indeed, the oxidation rates of chars from both bituminous coals and lignite, estimated based on the O-2 concentrations entering and exiting the Al2O3 reactor, were higher than their DMC counterparts. Moreover, graphite, containing no minerals and organically bound oxygen, has an even lower oxidation rate. Similar to those for the raw coals, the combined oxygen balance and elemental analysis of chars from DMC suggests that the oxygen in the organic portion of the lignite activates oxygen turnover and carbon oxidation during its combustion; neither chars from raw nor demineralized bituminous coals possess these properties. X-ray photoelectron spectroscopy (XPS) of raw and demineralized bituminous coals and their char show peaks at around 532.0 eV in the O(1s) difference spectrum, suggesting the possible existence of intercalated stable surface oxides.