Northwest Africa 14991 (NWA 14991)

(Northwest Africa)

Purchased: 2021

Classification: Carbonaceous chondrite (CM2)

History: Purchased by Ziyao Wang in Algeria from a meteorite dealer in May 2021.

Physical characteristics: Many identically appearing pieces. Dark fusion-crusted exterior, broken surface reveals numerous small chondrules set in a dark gray matrix that makes up over 50% of this meteorite. Small CAIs are visible.

Petrography: (A. Ross and C. Agee, UNM) Microprobe and reflected light microscopy examination reveal a fine-grained matrix that gives low microprobe totals from the presence of hydrous phases. Many chondrules are porphyritic type I with predominantly forsteritic olivines. Matrix olivines are mostly fragmental and ferroan. Apparent mean chondrule diameter approximately 300 μm. Aluminous diopside, calcite, troilite, Fe-Ni sulfide, and low-Ni iron metal were detected.

Geochemistry: (A. Ross and C. Agee, UNM) Type I chondrule olivine Fa_1.2±1.0, Cr₂O₃=0.44±0.11 (wt%) n=8; ferroan matrix olivine Fa_29.2±15.0, Fe/Mn=82±20, Cr₂O₃=0.29±0.10 (wt%) n=7; low-Ca pyroxene Fs_7.5±10.6Wo_2.1±2.1, n=6; matrix (20 μm defocused microprobe beam) analytical totals of 76.0±3.3 wt% and FeO=34.1±5.6 wt%, n=3.

Classification: Carbonaceous chondrite (CM2). The low analytical totals in the matrix indicate the presence of hydrous phases.

Specimens: 12 g on deposit at UNM, WangZ holds the main mass.