A guide to the Mule Creek volcanic vent, the rhyolite of Potholes Country, and obsidian ledges, Gila National Forest, southwestern New Mexico

1⁄2-min quadrangle (Ratte and Brooks 1989) is a worthwhile destination for anyone studying rhyolite volcanism in southwestern New Mexico. Directions for accessing the vent are followed by a discussion of the geologic setting, petrography and chemistry of the Potholes Country rhyolite, and economic considerations of this and other rhyolite bodies of similar age in the region. The Mule Creek vent of the rhyolite of Potholes Country is spectacularly exposed over a vertical distance of approximately 1,100 ft (350 m) in the south-facing wall of the canyon of Mule Creek (cover). The vent is approximately 7 mi (10 km) north of the settlement of Mule Creek, which is approximately 5 mi (3.5 km) east of the Arizona State line on NM‐78 (Fig. 1). The cover photo view shows the Mule Creek vent in total outcrop from the south rim of the canyon of Mule Creek. The outcrop probably rates as a world class geologic exposure of a rhyolite eruptive vent in cross section. The overview site from which the cover photo was taken can be reached from NM‐78 via Gila National Forest roads and a short jeep track that can be traversed in vehicles lacking four-wheel drive, but having high clearance.