Manganese-rich, aluminum-poor modulated layer silicate minerals are to be studied by using an integrated petrologic and mineralogic approach to assess structural stability. This study will determine if the misfit between the ideal sheets of tetrahedra and octahedra is a requirement to produce a modulated layer silicate structure. In addition, the Grenfell deposit, Australia, will be studied to determine the effect of sequential metamorphism on the mineral phases. The work will be done in collaboration with Dr. R.A. Eggleton of the Australian National University, the Canberra. Using ultra-high resolution transmission electron microscopy (TEM) and X-ray diffraction techniques.