Located south of Picacho State Recreation Area is the Copper Basin fault. The fault generally strikes ~EW and dips 56° S placing Jurassic (~161 Ma) gneiss over ~25 Ma Quechan volcanics. As it is traced westward, it breaks up into at least two imbricates. Here I focus on the most northward imbricate. At the study location, the fault zone of the hanging wall of the northern imbricate can be subdivided into a fault core and damage zone. Fragmentation and grain size comminution increases toward the fault core, and through three distinctive textural zones of the damage zone. The latter features are referred to, from outermost to the fault core, as damage zones 1, 2, and 3. Grain density systematically decreases toward the fault core, while bulk density remains relatively constant throughout the fault zone. Similar to grain density, porosity also decreases toward the fault core. Three samples were evaluated for their clay mineralogy. The < 2 micron fraction analyzed from damage zone 2 is composed of montmorillonitic smectite. In contrast, the < 2 micron fraction evaluated from the innermost part of damage zone 3 is composed of montmorillonitic smectite and calcite. A sample analyzed from the fault core contained significant amounts of calcite and montmorillonitic smectite. In addition, the sample from the fault core also contained mixed-layer illite/smectite (I/S) with 10% illite. These data as a whole, suggest that fluids were focused through the fault core relative to the adjacent damage zone, and implies that significant mass redistribution may have occurred within the core.