
Crystallisation of Magma
Magma: sticky or runny?
Magma can have different compositions depending on how it was formed. Magma also varies in temperature, and in how much dissolved gas it contains.
All of these factors control the viscosity of the magma (whether it is relatively runny or very thick and sticky).
Viscosity, in turn, controls how magma behaves as it rises through the crust, and erupts at the surface.
All of these factors control the viscosity of the magma (whether it is relatively runny or very thick and sticky).
Viscosity, in turn, controls how magma behaves as it rises through the crust, and erupts at the surface.
Cooling rate and grain size:

Volcanoes:

Igneous intrusions:

