Grain boundaries in mineral systems

The ideas about the structure of GBs and the methods for imaging them by TEM that were discussed in Section 5.3.8 evolved from studies of GBs 

3 Boundaries D and E (and the very low-an e boundary G) are seen to be arrays or networks of dislocations. 

It is clear from the observations summarized in this section that there is still a great deal to learn about the structures of GBs in mineral aggregates and rocks. Although the currently available techniques will no doubt yield further useful information, significant progress may depend on the development of novel techniques of specimen preparation, diffraction, and imaging. 

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