By Name A list of minerals in alphabetical order By Class Elements, Oxides, Carbonates, etc. Interesting Groupings Gemstones, Birthstones, etc. Between the tetrahedral sheets and linking the tetrahedral sheets are metal cations in 8 coordination. Dispite the layered structure, cleavage is all but completely absent.
Some members have beryllium instead of boron in the non-silicate tetrahedrons.
Several members have rare earth metals as part of their compositions.