Yucca 032        34°44.17’N, 114°13.05’W

Arizona, United States

Find: 20 Apr 2004

Classification: Ordinary chondrite (H3-5)

History: Found by Jerry A. Baird on April 20, 2004, one of several stones found by him at this location and lumped together as JAB 010.

Physical characteristics: Brownish and yellow-brown weathering patina occurs on rough exterior surfaces. Large fractures filled with a white precipitate are visible cutting across the hand specimen.

Petrography: In thin section, composed mostly of an intimate mixture of mineral and chondrule fragments with diverse (type 3-5) characteristics; one discrete type 3 chondritic clast is present. BSE imaging shows that most of the rock ("host") is composed of type 4-5, with plagioclase up to 50 μm across and equilibrated olivine, but that type 3 fragments including olivine zoned to more magnesian and ferroan compositions and feldspathic glass also are present. Abundant chromite-plagioclase assemblages are present. Numerous subparallel hydroxide veins cut across the section, with ~70% of the metal and ~40% of opaques overall being replaced, consistent with a high W2 weathering grade. Calcite is present in small void spaces. Elongate metal and sulfide grains are roughly parallel to the weathering veins. Olivine grains are heavily fractured by weathering veins, and most show undulose extinction with irregular to planar fractures, consistent with shock stage S3. A small melt pocket containing metal/sulfide droplets was observed.

Geochemistry: (M. Hutson and A. Ruzicka, Cascadia) Host dominated by equilibrated olivine (median Fa_17.7, N=56) and low-Ca pyroxene (median Fs_15.1, N=39). Overall average for host including mixture of both equilibrated and more varied compositions is olivine (Fa_14.8±5.8, range Fa_0-23.4, N=56), low-Ca pyroxene (Fs_13.7±4.3Wo_1.2±1.1En_85.1±4.3, range Fs_3.2-19.5, N= 39). Discrete type 3 clast, olivine (Fa _13.3±8.8, N=146), low-Ca pyroxene (Fs_10.6±9.6Wo_1.5±3.8En_87.9±10.8, N=108).

Classification: H3-5 finely intermixed genomict breccia. H group implied by prevalent silicate compositions. Type 4-5 lithology implied by maximum feldspar grain size and equilibrated olivine and pyroxene; type 3 lithology implied by presence of feldspathic glass and zoned olivine grains as well as discrete type 3 chondrite clast.

Specimens: Cascadia holds 95.4 g in multiple pieces, in addition to two polished thin sections and a mounted butt.