The Currant Tuff was named by Faust and Callaghan (1948) for exposures near the Ala-Mar Mine in Sec. 34, T.12 N., R. 59 E., in the northern Horse Range.

The Currant Tuff is Oligocene and has been dated at 31.7 +/- 1.2 Ma (Kleinhampl and Ziony, 1985). General Lithology

The Currant Tuff is composed of creamy water-lain tuff, white to yellowish-gray tuffaceous sandstones, and local patches of medium to coarse-grained, gray tuffaceous limestones (Faust and Callaghan, 1948). These tuffaceous sediments contain abundant fragments of pumice and crystals of quartz, feldspar, and biotite (Moores and others, 1968). The massive volcaniclastic sandstones as well as minor amounts of volcanic-pebble conglomerate were derived from the underlying ash-flow tuffs (Kleinhampl and Ziony, 1985).

The Currant Tuff reaches a maximum thickness of about 1,000 feet in the Currant area of the Grant Range (Moores and others, 1968).

The Currant Tuff is exposed in the Grant and Quinn Canyon Ranges within the evaluation area.