Abstract The route retraces the previous day's log as far as Santa Ana and then turns west on Mexico 2 highway towards Caborca. Subsequently at Km 43.5, the graded dirt road to the south leads to Trincheras. From this small community, situated on the railroad, a dirt road heads to the southwest and passes between El Boludo, a small rounded hill made up of Proterozoic dolomite and quartzite, and the Sierra La Salada that is largely underlain by biotitic granite, gneiss, mica schist, and epidote-bearing granite. This locality, and La Cienega area located 35 km further southwest, are part of the well-known gold placer deposits that have been exploited at various scales for more than 200 years. Nearby, on the western flank of Sierra La Salada, is the modern dry-washing plant at El Tiro. From there a brief visit to the Cerro Colorada gold prospect will be made before tracing the route to Santa Ana and Estacion Llano. Finally, the route follows near continuous outcrops of the Sonoran batholith southward to Hermosillo.

Abstract The Coles Hill uranium property is located in Pittsylvania County, Virginia, within the Smith River allochthon in Southside Virginia's Western Piedmont Province. The Coles Hill property is bounded on the east by the listric normal Chatham fault at the Triassic Danville basin. Uranium mineralization occurs in the footwall of the Chatham fault and is hosted in healed fractures and in hydrothermal apatite in the Leatherwood granite mylonite that is intruded by the Rich Acres gabbro amphibolite. The granite is silica depleted. The mylonite is foliated with a strike of 030° and dips 30°SE; the Chatham fault strikes 030° and dips 60°SE. The structural trap for uranium mineralization is contained on the east by the Chatham fault and beneath by unmineralized Leatherwood biotite gneiss, which is underlain by the Fork Mountain schist. Hematite staining of the ground surface is from weathering of Fork Mountain schist, which outcrops west of the Chatham fault at a constant distance of half a kilometer. In the southern property, pods of uranium mineralization plunge south at 45°. In the northern property, pods of uranium mineralization plunge northeast at 12°. Saussurite, rapakivi textures, Na- and K-metasomatism, titanite, zircon, apatite, calcite, and hematite are present. One possible uranium source is remobilization from the Triassic basin by westward-flowing meteoric waters that intersected the Chatham fault at depth and migrated upward and laterally into the Leatherwood granite. Another uranium source model may be introduction of uranium mineralization by hydrothermal fluids associated with emplacement and cooling of the Leatherwood granite. These fluids would have migrated upward into a structural trap where uranium minerals were precipitated in hydrothermal fractures.