Spodumene at Pressure
Using Arlt and Angel (2000) data we plot a model for the bonding changes that occur in spodumene as a function of pressure. The structure adopts C2/c symmetry at room conditions and adopts P21/c symmetry at pressures greater than 3.2 GPa.

Optical view of the high pressure phase transition in spodumene in a diamond anvil cell at 3.2 GPa. The screws on the diamond anvil cell are adjusted, which changes the volume inside the cell. The pressure does not change. Instead the crystal volume changes by undergoing a phase transition. The two phases display different colours under a polarizer. This image comes courtesy of Thilo Arlt.