Eutectic intergrowth textures

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Eutectic intergrowth textures can occur for many minerals, but a specific terminology is used for quartz and feldspar.

Graphic intergrowth – alkali-feldspar crystalizing before quartz. Alkali feldspar and quartz co-crystallize at the eutectic, however, in undercooling conditions (related to a strong temperature gradient), alkali-feldspar crystallizes rapidly and before quartz (the magma near the growing feldspar then becomes saturated in silica and quartz crystallizes).

Granophyre texture – quartz and alkali-feldspar co-crystallizing at the eutectic (usually occurs in water-rich magma, or in undercooling condition).

Lattice intergrowth (to come)