Northwest Africa 11121 (NWA 11121)

(Northwest Africa)

Purchased: 2004 Feb

Classification: Ordinary chondrite (H3-6)

History: A single stone was obtained by Edwin Thompson from a Moroccan Trader in Tucson, Arizona, at the February 2004 Tucson Gem and Mineral Show; a portion (53 g) was donated to Cascadia on Feb. 28, 2004.

Physical characteristics: Weathered patina, dust, and fusion crust partly cover exterior. Cut faces reveal a light brown to grey interior with chondritic texture (abundant metal, chondrules, fragments) as well as two types of clasts up to 2 cm across, including light, partly reddish stained clasts with coarser metal, and darker clasts with finer metal.

Petrography: (A. Ruzicka and K. Farley, Cascadia) A breccia composed of a mixture of mineral and chondrule fragments and some larger clasts, including a partly fragmented type 6 clast with feldspar often >50 μm across corresponding to the larger light clasts seen in cut faces, and a type 3 clast with well-defined chondrules (some glass-bearing) corresponding to the larger dark clasts seen in cut faces. Host areas between these larger clasts contain chondrule fragments of various textures down to progressively smaller sizes.

Geochemistry: Mineral compositions and geochemistry: (K. Farley and A. Ruzicka) Larger type 6 clast includes olivine (Fa_19.1±0.6, N=33), low-Ca pyroxene (Fs_17.6±0.6 Wo_1.5±0.3, N=22), and feldspar (Ab_79.7±1.5Or_6.6±1.2, N=15); larger type 3 clast includes olivine (Fa_15.0±8.2, N=23) and low-Ca pyroxene (Fs_15.3±8.7Wo_2.2±1.4, N=23); host includes olivine (Fa_17.6±5.5, N=27), low-Ca pyroxene (Fs_16.3±4.1Wo_1.6±0.7, N=22), and feldspar (Ab_84.3±6.0Or_4.8±2.0, N=5).

Classification: H3-6 genomict breccia. Larger clasts consist both of type 3 and 6 lithologies and the host appears to be composed of an intimate mixture of smaller fragments of the same type of material.

Specimens: Cascadia holds three pieces (32.0, 16.6, 0.8 g), a polished thin section, and a potted butt. Thompson holds the main mass.