This represents a continuation of support for research previously funded by NSF grant EAR 8408168 and amendments, involving the use of transmission electron microscopy to study local regions of structural and chemical disorder in minerals. Specific studies include: high- resolution imaging of illite/smectite to determine details of intercalations and ordering, of defects in perovskite synthesised at high pressures, of stacking sequences and disorder in graphite, of interralationships among iron-rich silicates in iron formations, of series of manganese oxides and silicates, and of the nature of gold occurrence in sulfide minerals. Detailed observation of such regions can provide data on chemical and physical properties of the host minerals and can give insights into their origin and history.
