Some anorthosite-troctolites in the Proterozoic Lac St Jean anorthosite complex are almost undeformed and preserve interesting outcrop-scale field relationships and textures. The plagioclase crystals within large olivine oikocrysts preserve a time-sequence of the formation of anorthosite. Crystal size distributions indicate that initially plagioclase nucleated and grew in an environment of increasing undercooling, producing a straight-line CSD. During this phase, latent heat of crystallisation was removed by movement of a crystal-magma slurry or by circulation of magma through the porous crystal mush. By about 25-30% solidification the crystallinity was such that it reduced, but did not eliminate, the circulation of magma, resulting in the retention of some of the latent heat within the crystal pile. The resultant increase in temperature both inhibited nucleation and encouraged recrystallisation. Small crystals started to be resorbed, but larger crystals continued to grow, both from new material and that recycled from the resorbtion of the microcrysts. This process differs from simple adcumulus growth in that it starts very early in the solidification, about 25%, and involves the solution of smaller crystals. Modelling of the shapes of the CSDs indicates that the commonly proposed Oswald Ripening process cannot be correct, and crystal growth (and solution) must follow other processes, such as Lateral Growth. The dominance of recrystallisation during the solidification of these rocks may account for field evidence of olivine solution, hence anorthositisation of troctolite, from adjacent outcrops. This process of nucleation suppression and recrystallisation may be important in the formation of monomineralic and other plutonic rocks.