Named for exposures in the Chico Shunie Hills, Pima Co, AZ in the Southwestern Basin-and-Range region. Crops out over a 10 sq mi area. No type locality designated. Forms gently rolling topography. Disintegrates readily. Intrudes the Cardigan gneiss (new); contact is usually sharp. Is variable in composition. Most abundant rock type is pink-gray (fresh), brown (weathered), massive, coarsely porphyritic quartz monzonite though variations to potash granite, albite granite, and quartz diorite are common. Typically crystals of pink feldspar, 1+/-inch long occur in a coarse groundmass of quartz, biotite (altered to chlorite), white feldspar, a little epidote. Gray alaskitic rocks are widespread. Coarse pink pegmatitic gneisses with rounded pink feldspar crystals occur in the Chico Shunie. Was deformed prior to intrusion of the Cornelia quartz monzonite (new). Unconformably overlain by the Locomotive fanglomerate (new). Tentatively assigned to the Mesozoic. Geologic map.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Forms gently rolling hills in eastern part of area around Tepee Butte and Chico Shunie Arroyo, Pima Co, AZ in the Southwestern Basin-and-Range region. Dominant rock type is quartz monzonite. Also includes albite granite, quartz diorite, and trondhjemite. Age modified from Mesozoic? to Proterozoic because an amphibole from a pegmatite dike that cuts Chico Shunie had a 1.4 b.y. K-Ar date.

Source: GNU records (USGS DDS-6; Denver GNULEX).