X-Ray Diffraction | Mineral Thin Section |
Crystal Form
Like the other common silica dioxide minerals there are two different forms of cristobalite; the alpha phase and the beta phase. Because these phases exist in different temperatures they do not share the same crystal structure. The low-temperature alpha phase is a tetragonal from of space group P41212. The high-temperature beta phase is a isometric cube from of space group Fdh. Twinning on the cristobalite crystals are common, interpenetrate, polysynthetic and repeat. Cristobalite has two forms, a high temperature (beta) and a low temperature (alpha). The beta form has a silicon atom structure arrangement of carbon atoms in diamonds. β-Cristobalite is stable from a temperature of 1470℃ and melts at 1728℃, anything below this point is metastable.
Atomic Struture
Alpha-cristobalite form This is the crystal structure of an alpha cristobalite. As you can see the structure is very orderly and in linear patterns.  | Beta-cristobalite form This is a sample of the crystal structure of beta-cristobalite. The structure it is form is very disordered and not in defined linear patterns.  |
