Crystallization Sequences
Discontinuous - Olivine begins to crystallize at high temperatures
At some lower temperature olivine reacts with the liquid and a pyroxene forms
Continuous - there is a continuous variation in composition within the Plagioclase Solid Solution Series
At much lower temperatures Alkali Feldspar and Quartz crystallize from the melt
Viscosity - the resistance a liquid offers to flowing : high viscosity - very sticky and liquid flows with difficulty