Zonation

Title

Zonation

Subject

As a crystal grows slowly in a magma chamber the magma from which it is crystallising may evolve, changing its composition. Thus later crystallising regions or “zones” of the crystal will have a slightly different composition from earlier crystallising regions. The crystal thus displays zonation.
Zonation is seen under cross-polarised light by variations in the birefringence colours of the different zones.

Description

Have a look at the granodiorite (L120) in the 1A Reference Series.

Collection

Citation

“Zonation,” 1A Collections, accessed February 27, 2020, https://wserv3.esc.cam.ac.uk/p1acollections/items/show/267.