The montmorillonite group, which often occurs in the drier tropics, has two silica layers for every one gibbsite.    From Wordnik.com.  [Chapter 5] Reference

In its molecular structure thousands of alternate flat layers of silica (silicon oxide) and gibbsite (aluminium oxide) occur, and give the particles their typical hexagonal plate-like structure.    From Wordnik.com.  [Chapter 5] Reference

These minerals are gibbsite (Al (OH) 3), diaspore (AlO (OH)), and boehmite (AlO (OH)).    From Wordnik.com.  [Aluminum] Reference

The principal minerals from which aluminum is recovered today are hydrous aluminum oxides, the most prominent of which are bauxite, gibbsite, and diaspore -- the aggregate of all these minerals going commercially under the name of bauxite.    From Wordnik.com.  [The Economic Aspect of Geology] Reference