Northwest Africa 17472 (NWA 17472)

Purchased: 2024    Classification: Martian meteorite (Shergottite)

History: Purchased by Mark Lyon and Craig Zlimen from Choaib Bdirina.

Physical characteristics: Two stones, 1.8 kg and 1.2 kg, found together, with weathered fusion crust. Freshly broken surface reveals gray pyroxene crystals and shiny maskelynite.

Petrography: (C. Agee, UNM) Electron microprobe analysis and reflected light microscopy of a polished mount show this meteorite to be a basaltic shergottite. The two major phases in this meteorite are clinopyroxene and maskelynite. Ubiquitous minor phases are merrillite, titanomagnetite, ilmenite, and troilite. The clinopyroxene has a modal abundance of approximately 50%, with significant core to rim zoning indicating an igneous crystallization trend with Mg-rich pigeonite cores, mantled by augite, and rimmed with ferropigeonite. Clinopyroxene average grain sizes are approximately 300-500 μm. Maskelynite has modal abundances of approximately 40%, and most grains are thin and elongate with maximum length ~1 mm.