Yucca 042        34°44.055’N, 114°12.397’W

Arizona, United States

Find: 10 Mar 2004

Classification: Ordinary chondrite (H3-6)

Petrography: In thin section, the sample appears to be relatively integrated, grading from material with a texture resembling a type 5 chondrite comprised primarily of chondrule fragments to material resembling a type 4 chondrite comprised of well-defined chondrules amidst chondrule fragments. Smaller chondrule and mineral fragments occur between chondrules and larger chondrule fragments; lithic clasts are absent. BSE imaging shows that most of the meteorite contains equilibrated silicate, but that there is a substantial (~10 area %) admixture of type 3 material (both magnesian and iron-rich zoned olivine and pyroxene grains). Most of the equilibrated material contains devitrified glass or small (< 50 μm) plagioclase feldspar grains; coarse (>50 μm) plagioclase is also present. Chlorapatite, merrillite, chromite-plagioclase objects, and metallic copper were observed.

Geochemistry: (M. Hutson and A. Ruzicka, Cascadia) Representative analyses for fragments and chondrules (both equilibrated and unequilibrated grains): olivine (Fa_18.9±5.4, N=104), low-Ca pyroxene (Fs_16.2±3.6Wo_1.3±0.8, N= 66), plagioclase feldspar (Ab_79.7±2.2Or_5.8±2.7, N=17).

Classification: Sample represents an intimate mixture of fragmental material. Type 3 is inferred from presence of zoned magnesian and ferroan olivine grains; type 6 from coarse (>50 μm) plagioclase feldspar grains. Sample is classified as an H3-6 genomict breccia. May be paired with Buck Mountain Wash (Yucca 002).

Specimens: Cascadia holds 28.6 g in multiple pieces, in addition to one polished thin section and a mounted butt.