Pneumatolysis is an obsolete geologic term for magma emitting gasses that alter surrounding rock or crystallize minerals. Pneumatolysis is now considered a type of hydrothermal interaction.

What is pneumatolytic metamorphism?

Contact metamorphism in which the composition of a rock has been altered by introduced gaseous magmatic material.

What is Pneumatolytic phase?

pneu·ma·tol·y·sis

A process of rock alteration or mineral formation brought about by the action of gases emitted from solidifying magma.