Potassic Micas and Mica-like Minerals

It is important to establish an initial basis in terminology for these minerals because the terms used have undergone a considerable 

10 per (OH) anionic charges. Such a structure has a basic crystallographic repeat distance (c sin 3) of 10 X + 0.2 when potassium Is the interlayer ion. Treatment with polar ions such as ethylene glycol does not change this distance nor does it change the shape of the X-ray diffraction peak present at 10 X. In the low temperature environments, 200°C, the dominant interlayer ion in micas is potassium, neither sodium nor calcic micas are stable (Chatterjee, 1968 Velde, 1971 Hemley, t al., 1971). 

Mica-llke phases have a c sin 3 spacing near 10 X, between 10,1-10.3 

This gives an idea of what is meant by mica and mica-like phase. 

The latter term can be described by several mineral names and will be discussed in some detail. 

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