Northwest Africa 16183 (NWA 16183)

(Northwest Africa)

Purchased: 2021 Sep

Classification: Ordinary chondrite (H4)

History: Mr. Jasper Spencer purchased three stones from a Mauritanian dealer in September 2021 via FB Messenger, and was told by the seller that these were found in Mauritania in 2021. Cascadia received an end cut with a mass of 80.3 g from the largest stone, which was 295 g before cutting

Physical characteristics: Physical Characteristics: The exterior portion of the end cut is entirely coated in a dark brown to black fusion crust. The cut surface shows abundant metal and sulfide grains. Numerous chondrules are visible, many partially or completely rimmed by metal.

Petrography: (G. Anim, D. Sheikh, M. Hutson, and A. Ruzicka, Cascadia) The thin section displays a closely packed aggregate of barred olivine, porphyritic olivine, porphyritic olivine pyroxene, radial pyroxene, cryptocrystalline pyroxene, and granular to microporphyritic olivine chondrules and chondrule fragments. Chondrules are well-defined and are set in a primarily black matrix containing abundant nickel-iron and troilite. Much of the metal and troilite contains angular silicate inclusions. A few metal grains contain rounded troilite nodules giving them a sort of boiled or fried egg appearance.

Geochemistry: Olivine: Fa_18.1±1.0 (N = 37); Low-Ca pyroxene Fs_15.7±2.8Wo_0.8±0.3 (N = 26).

Classification: Ordinary Chondrite (H4) based on mineral chemistry and texture.

Specimens: Cascadia holds 77.1 g in one piece, as well as one polished thin section and material in an epoxy stub. Mr. Jasper Spencer holds the main mass.