The distribution of primary minerals in a peat profile was investigated in a dated core (210Pb, 14C) taken from the upper part of an ombrotrophic bog. Using XRD, the most abundant minerals present in the peat were those of the local granite, suggesting that the dust entering the bog is mainly of local origin. Apatite and calcite are restricted to the top 8 cm of the profile, which suggests rapid dissolution. The release of P by apatite dissolution is possibly the main source of plant-available P to the oligotrophic waters. In contrast, quartz and feldspars appear to be preserved for thousands of years despite the low pH and abundance of organic acids. This study suggests that ombrotrophic peat bogs could be valuable archives of aluminosilicate deposition since the Late Glacial.