The underground Tiger Mine, active primarily during the first half of the 20th century, sits below the massive heap leach pile at San Manuel, southeastern Pinal County. Tiger Mine was renowned for its wulfenite specimens.
From the report that accompanied the 1:24k geologic map of the Mammoth quadrangle, "In the Tiger mine area, rhyolite, mafic lavas, and Oracle Granite are all brecciated, with varying amounts of each unit in the breccias. The breccias and rhyolites in the Tiger mine area wereemplaced across the east-northeast striking Turtle fault, and so post-date the fault."
Online resource:
Spencer, Jon E., Gootee, Brian F., Richard, Stephen M., and Cook, Joseph P., 2009, Geologic Map of the Mammoth 7.5' Quadrangle, Pinal County, Arizona: Arizona Geological Survey Digital Geologic Map DGM-67, version 1.0, map scale 1:24,000, 20 p. and 2 map sheets. http://repository.azgs.az.gov/uri_gin/azgs/dlio/624