Proposed to explain the juxtaposition of two distinctly different 'liquid' compositions with no intervening, intermediate composition.

e.g. globular masses of granitic composition in a basaltic matrix.

Varioles, spherulres ===> variolitic, spherilitic

This process has been in and out of favour with petrologists for the past century.

Liquid immiscibility has been proposed to have played a role in the formation, by fractionation, of:

1. Archaean volcanic rocks from the Abitibi Belt of NE Ontario and NW Quebec.
2. Lunar Mare Basalts. All Apollo missions returned samples exhibiting evidence for immiscibility.
3. Cretaceous deep sea basalts.

In all of the above ==> basalt host with 'granitic' globules or varioles.

Immiscibility has also been proposed and or observed for alkali intrusions, which may have two silicate liquids or a silicate and carbonate liquid, and mafic intrusions, which may have silicate and sulphide liquids.