We determined the physical, chemical, and mineralogical properties of six clay to heavy clay soils developed from lacustrine material in Abitibi, Quebec. Maximum clay content occurred in the B horizons, which generally also had the highest dry bulk density. Quartz, feldspar, and hornblende were present in the clay fraction of all samples in association with illite, chlorite, and vermiculite, which were the dominant clay minerals. Cation exchange capacity values ranged from 16 to 46 meq/100 g of soil and were significantly related to the clay content. The effect of organic matter on CEC was also evident in some Ap horizons.