geophase

plural geophases

1. geographyA point in the sequence of geochemical changes that occur as minerals are formed from cooling magma.

   […] contemporaneous with gold are gilbertite, leptochlorite, tourmaline, iron sulphides, feldspar, (rare) carbonates, and quartz; post gold minerals are quartz, zinc and lead sulphides, and many others of geophases K and L.

   2012, Robert W. Boyle, Gold: History and Genesis of Deposits, page 108

   1 more example

   In the opinion of A.E. Fersman, amazonite freely crystallizes from melt in the relatively late geophases of the pegmatite process, but the beginning of its formation belongs to the earlier and high-temperature geophase—the rise of graphic granite.

   2015, Mikhail Ostrooumov, Amazonite: Mineralogy, Crystal Chemistry, and Typomorphism, page 179