Potassium mica was treated with different ionic solutions to replace the naturally occurring K+ on the surface by Ca2+, Mg2+, and H+ ions. The extent of the exchange was monitored by variable emergence angle X-ray photoelectron spectroscopy (XPS). Scanning polarization force microscopy (SPFM) was used to measure the mobility of the surface ions as a result of water adsorption when the mica is exposed to different humidity levels.