Pentagonite is a silicate that is considered “unclassified”. Its silicate backbone is similar to that of a phyllosilicate structure except that alternating pairs of tetrahedra are inverted.
Highlighting FeaturesSilicon (Si) atoms A silicate sheet Calcium (Ca) atoms Vanadium (V) atoms Single unit cell All atoms
Evans, H.T. 1973. The crystal structures of cavansite and pentagonite. American Mineralogist 58:412-424.