In the Jimberlana Norite the heteradcumulate and adcumulate rocks are found in adjacent layers. The heteradcumulate occur immediately before the heterad minerals appear as cumulus grains in an adcumulate rock. It is considered that both heteradcumulate and adcumulate textures result from supercooling in the magma. Heteradcumulates develop when seeds of the heterad mineral are not available in the magma and adcumulates after they have formed. © 1968, Cambridge University Press. All rights reserved.