Muscovite mica, interactions between

The LB monolayers of dimethyldioctyadecylammonium ions on molecularly smooth muscovite mica surfaces were investigated. Direct measurements of the interaction between such surfaces were carried out using the surface force apparatus. A long-range attractive force considerably stronger than the expected van der Waals force was measured. Studies on the electrolyte dependence of this force indicate that it does not have an electrostatic origin but that the water molecules were involved in this. 

Figure 6.3. Measured values of the force F between two muscovite cylinders of radius i as a function of their separation d in aqueous solutions of KNO3. The ratio FI27tR equals the potential energy per unit area for the interaction between the two mica surfaces.

Interactions between polyelectrolyte-coated surfaces in the absence and presence of SDS were examined using the interferometric surface force technique of either the Mark II type [12] or the Mark IV type [13]. Muscovite mica was obtained from Mica New York Corp. in New York (green mica) and from M. Watanabe Co. in Tokyo (ruby mica). It was cleaved to 1-3 m thin pieces and silvered on one side. The pieces were then glued (using Epon 1004 from Shell Chemicals) onto two half-cylindrical silica discs with the silvered side down. The surfaces were mounted in a crossed cylinder configuration inside the surface force apparatus with the upper surface connected to a piezoelectric tube and the lower one on a double cantilever spring. The distance between the surfaces in changed by means of motors or by means of the piezo-electric crystal. 

The long time scales (104 to 10s m.y.) involved in deformation and synkinematic isotope exchange in white mica provide a robust, long-term average of meteoric water-rock interaction, characteristic for the time scales of major readjustments in surface elevation. Thus the hydrogen isotope record in recrystallized muscovite provides a direct link between the tectonic and fluid flow history in the shear zone and temporal variations in meteoric water composition due to changing surface elevation. 

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