We have investigated the surface properties of quasicrystalline and approximant phases in the Al-(Cu)-Cr-Fe system upon aging in ambient conditions. We found that some of these properties (like the electrochemical behavior, wetting or friction) slowly evolves with the length of exposure to normal atmospheric conditions, reaching a stable state only after several days. This report essentially focuses on one of these alloys, an Al65Cr27Fe8 approximant phase with g-brass structure. In a first part, we describe the effect of aging on the electrochemical behavior of this alloy and we propose an interpretation based on a simple electrical model of the oxidized surface. In a second part, we present a model describing the surface as a stacking of several layers (oxides, oxy-hydroxides, contamination) whose thickness evolves with time. The model is supported by X-ray reflectivity, angle-resolved photoemission spectroscopy and secondary neutral mass spectroscopy measurements.