Small but prominent feature rising 128 feet above the surrounding desert floor. Naming credit goes to HAZ user Dave1.

Geologic information:
Crystal-poor andesite (Early Miocene or Late Oligocene) -- Crystal-poor, pyroxene-porphyritic lavas of probable trachyte, basaltic andesite, or andesitic composition characterized by pyroxene-porphyritic texture and finer grained sparse plagioclase phenocrysts. Brown iron oxide(?) minerals typically replace sparse I-mm pyroxene phenocrysts. Locally this unit contains vesicles or amygdules, fresh pyroxene, or abundant plagioclase micro lites. These lavas occur at the top of the volcanic sequence in a very thick succession of amalgamated flows or flows with thin intervening volcaniclastic or pyroclastic intervals (Tvs). Flows with similar phenocryst mineralogy are present at the base of the section in the southeast where they are mapped as older andesite (Tao).

An isolated hill between Picacho Peak and the Picacho Mountains (HAZ defined Turd Hill) is probably composed of this unit, but extreme alteration has obscured phenocrysts and it is uncertain if this unit actually is part of the crystal-rich andesite (map unit Tac). A sample from this hill analyzed by Brooks (1986) contained 11.0% K20 and only 0.8% Na20 (K20INa20 = 13.7), which indicates severe potassium metasomatism.

Source:
Geologic map of the Picacho Mountains
and Picacho Peak, Pinal Connty,
Southern Arizona
by
Stephen M. Richard, Jon E. Spencer, Charles A.
Ferguson, and P. A. Pearthree
Arizona Geological Survey Open-File Report 99-18
September, 1999
http://repository.azgs.az.gov/uri_gin/azgs/dlio/377