Yucca 046        34°46.009’N, 114°14.415’W

Arizona, United States

Find: 12 Oct 2011

Classification: Ordinary chondrite (H3-5)

History: Found by Jim Wooddell on October 23, 2011 while searching with a metal detector. Mr. Wooddell donated the entire stone to Cascadia in September, 2013.

Physical characteristics: Brownish weathering patina occurs on exterior surfaces.

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 an abundance of magnesian and iron-rich olivine and pyroxene grains, many of which show zoning, and which abut equilibrated fragments with typical H-chondrite compositions. Laths of a silica polymorph were observed, as well as several small chromite-plagioclase objects and merrillite grains up to 250µm across. Feldspathic material consists of glass of variable compositions and crystalline plagioclase feldspar grains typically 20-40 µm across; no grains larger than 50 µm across were observed. A single fragment 70 µm across appears to be a typical type 3 matrix lump, found adjacent to a crystalline feldspar grain. Both high- and low-Ca aluminous pyroxenes (up to 6.7 wt% Al) were observed in three chondrule fragments and as single grains, sometimes with anorthitic glass, and sometimes with forsteritic olivine (Fa<5), and spinel. In addition to these small spinel grains, an isolated zoned spinel grain (100 µm across) was observed. Fe-Ni carbide was found, along with magnetite; in one clast magnetite appears to be replacing troilite.

Geochemistry: (M. Hutson and A. Ruzicka, Cascadia) Sample contains a wide range of compositions of olivine (Fs_20.1±6.0, N=51), low-Ca pyroxene (Fs_15.6±5.3Wo_1.2±1.0, N= 61).

Classification: Metal abundance (9 area%) is consistent with an H chondrite. 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, suggesting that this 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 9.0 g in two pieces, in addition to a polished thin section and a mounted butt.