ERSC 2P21 Lecture Notes - Lecture 19: Crystal Growth, Pegmatite, Rhyolite
20 Dec 2018
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Document Summary
Crystallization involves two different processes: nucleation (formation of a seed , crystal growth (diffusion controlled) Growth only occurs after a nucleus(seed) has formed. Requires some degree of supersaturationof the constituent ions in the host solution (water or magma). Crystal growth and nucleation rates are affected by the rates of changein temperature, pressure, composition. H2o (and other volatiles like co2, f, cl) in a magma will inhibit crystal nucleation, but will facilitate crystal growth, driving the magma to crystallize larger minerals (a pegmatite). rhyolite granite. As a vapourcools, dissociated atoms or molecules combine to form crystalline solid. Lower energy to grow from the corner and step than the terrace. In some less ionicallybonded minerals, clusters of atoms will accrete to the surface. Important points: the rate of growth determines which crystal lattice face will become prominent in a crystal, the slowest growingfaces are usually the most prominent in a crystal"s external morphology!
