Two zircon fractions from sample of gray, fine-grained, mildly to strongly foliated porphyritic metarhyolite has yielded an age of about 155 to 160 Ma. Planet is mapped in the western Buckskin Mountains of La Paz Co, AZ, Basin-and-Range province.

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

Named for Planet Wash. Type locality is along the west side of the wash in the center of the east half of sec 7, T10N, R16W, Mohave Co, AZ in the Plateau sedimentary province. "Reference localities" are along Mineral Wash in center of sec 11, T10N, R17W. Overlies Vampire Formation (new). Consists of quartz-feldspar-muscovite-magnetite schist that is homogeneous in composition over tens to hundreds of meters. Feldspar and quartz phenocrysts make up 2 to 20 percent of the rock. Other lithologies include volcaniclastic sandstone with quartz and feldspar grains, weakly foliated, blocky, red-weathering silicic volcanic rocks with quartz and feldspar phenocrysts, and chloritic schist. Represents metamorphosed silicic ash-flow tuff, volcaniclastic rocks, and possibly hypabyssal intrusive rocks. The chloritic schist may include hydrothermally altered volcanics. East of Mineral Hill mine some 1 to 20 m thick quartzite beds present in basal 100 m of Planet that are interbedded with metavolcanic and metavolcaniclastic units may be of eolian origin. Is up to 600 m thick. One sample yielded an age of about 160 Ma by U-Th-Pb analyses on zircon. Next younger unit is some sedimentary rocks of Miocene age.

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