Dried surface sediment from various Canadian lakes was characterized by X-ray diffraction and Mössbauer spectroscopy. At most two quadrupole doublets were found at room temperature, one ferrous, the other largely ferric. Their intensity ratio is related to the crystallinity of the sediments. It is also correlated with oxygen content, and inversely correlated with ferrous iron content of the overlying water. The major iron phase in the sediments is X-ray amorphous ferric hydroxide. Chlorite is the major ferrous mineral.