What is the difference between aphanitic and fine grained

In general, the slower the cooling, the larger the crystals in the final rock. Because of this, we assume that coarse grained igneous rocks are "intrusive," in. Crystals in magma grow in a similar way as the melt cools. and the resulting rock is fine-grained, with crystals usually less than 1mm in size. Most aphanitic rocks are characterized by mineral grains less than Many fine-grained allotriomorphic-granular rocks are more simply termed sugary.