A Clathrate Crystalline Form of Silica

The low-density cubic form of silica (impure), melanophlogite, has a clathrate-type structure that incorporates organic molecules, including long straight-chain hydrocarbons. The structure is analogous to that of the clathrate crystalline hydrates of composition 6X.46H(2)O or 8X.46H(2)O. This is the first known example of a silicate framework structure with the pentagonal dodecahedron as a framework element.