Yucca 050        34°48.036’N, 114°15.346’W

Arizona, United States

Find: 25 Nov 2011

Classification: Ordinary chondrite (H3-5)

History: Found by Wendy Wooddell on November 25, 2011

Physical characteristics: Sample has weathered fusion crust on one side. All other exterior faces are broken surfaces which are medium-brown from weathering, showing numerous small protruding dark bumps, which appear to represent weathered metal grains

Petrography: In thin section, the sample appears to be relatively integrated, with many chondrule fragments and only a few complete chondrules present; distinct lithic clasts typical of a breccia are absent. The material between chondrule fragments is comprised of individual grains and smaller fragments. BSE imaging shows that most of meteorite consists of fragmental material, with about a 10% admixture of magnesian and iron-rich olivine and pyroxene grains, many of which show zoning, and which abut equilibrated fragments with typical H-chondrite compositions. Numerous chromite-plagioclase objects were observed, including a fragment containing chromite-plagioclase pseudomorphs after a lath-shaped phase set in a feldspathic matrix. Throughout the section, feldspathic material consists of glass of variable compositions and crystalline plagioclase feldspar grains typically 20-40 µm across; a few grains up to 70 µm across were observed. Also present are merrillite grains, some up to 250 µm across. Fe-Ni carbide was found, along with ilmenite and magnetite.

Geochemistry: (M. Hutson and A. Ruzicka, Cascadia) Sample contains a range of compositions of olivine (Fa_18.7±2.2, N=31) and low-Ca pyroxene (Fs_15.2±3.6Wo_1.6±0.8, N= 44).

Classification: Meteorite is an H-chondrite, based on chemistry. Although the chemistry and abundance of zoned grains suggests a type 3 designation, the presence of medium-sized crystalline feldspar, coarse phosphate, and chromite-plagioclase objects suggests a higher petrographic type. The thin section studied strongly resembles the "main" lithology found in the Buck Mountain Wash chondrite, which is an H3-5 finely intermixed genomict breccia. Paired with Buck Mountain Wash (synonymous with Yucca 002) on the basis of mineralogy, mineral chemistry, and texture.

Specimens: Cascadia holds 23.4 g in one piece, in addition to three polished thin sections. Wendy Wooddell retained a 3.8 g end piece.