How do bond angles change when framework minerals are compressed?

In framework minerals, which are composed of corner-linked clusters of atomic polyhedrons, compression occurs significantly through the bending of metal-oxygen-metal bond angles between these polyhedrons.1

As pressure increases, these angles change to allow for the collapse of interpolyhedral spaces. This mechanism is highly efficient for volume reduction; the resulting volume change is typically an order of magnitude greater than the volume change caused by bond-length shortening alone. Consequently, framework structures are often much more compressible than structures where polyhedrons share edges or faces, as the latter rely predominantly on bond compression.1