These frameworks are composed of SiO4 tetrahedra in which every oxygen atom is shared with a neighbouring tetrahedron, so that the chemical formula of silica is SiO2.

The dynamically disordered nature of the β phase is partly responsible for the low enthalpy of fusion of silica.

96, at random) occurs on cooling below about 250 °C at ambient pressure and is related to the cubic form by static tilting of the silica tetrahedra in the framework.

It may be termed "displacive"; i.e., it is not generally possible to prevent the cubic β form from becoming tetragonal by rapid cooling.

The tetrahedra remain fairly regular and are displaced from their ideal static orientations due to the action of a class of low-frequency phonons called rigid unit modes.

In β-cristobalite, there are right-handed and left-handed helices of tetrahedra (or of silicon atoms) parallel to all three axes.

The new "a" lattice parameter is shorter by approximately the square root of 2, so the α unit cell contains only 4 silicon atoms rather than 8.)

These different twin orientations coupled with the discontinuous nature of the transition (volume and slight shape change) can cause considerable mechanical damage to materials in which cristobalite is present and that pass repeatedly through the transition temperature, such as refractory bricks.

Cristobalite occurs as white octahedra or spherulites in acidic volcanic rocks and in converted diatomaceous deposits in the Monterey Formation of the US state of California and similar areas.