The mobility and conditions for isomorphic substitution of alkali and interlayer water in micas have been investigated by means of infrared spectroscopy and radioactive tracer technique. Dioctahedral and trioctahedral micas have been treated with the following radioactive and non-radioactive reagents: deuterium oxide, tritiated water, rubidium 86, potassium 42, l molar solutions of LiCl and RbCl in tritiated water.
Diffusion experiments prove that a great part (the greater part?) of diffusion follows cracks and defects in the mineral lattices, prohibiting accurate determination of diffusion constants and diffusion anisotropi.
The influence of broken bonds along edges and defects upon the fixation of adsorbed ions is proved by autoradiographs. The substitution of alkali ions in the interlayer position by neutral water molecules in case of hydrous micas is made probable. The charge balance in this case may either be caused by a proton or a Li ion entering into the vacant position of the octahedral layer in the dioctahedral micas. By trioctahedral micas the hydrous varieties seem to represent mixed layer systems between ideal alkali mica (phlogopite) and vermiculite.