Northwest Africa 12594 (NWA 12594)

Algeria

Purchased: 2018

Classification: Martian meteorite (Shergottite)

History: Found in Algeria in 2018 and purchased from a Moroccan dealer by Huapei Wang in 2018

Physical characteristics: These stones are (partially) covered by black fusion crust and appear to be very fresh and unaltered. Numerous vesicles are seen in the fusion crust. The interior is composed of yellow green grains with interstitial pale gray grains.

Petrography: The rock has a medium-grained subophitic texture. It consists of elongated prismatic pyroxene (up to 1.5 mm in length) and lath-like plagioclase (up to 1.8 mm in length), with accessory titanomagnetite, ilmenite, silica polymorph, merrillite, pyrrhotite, fayalite. Pyroxenes show patchy zoning from Mg-rich core to Mg-poor rim, with irregular boundaries. Ilmenite occurs as thin lamellae intergrown with titanomagnetite.

Geochemistry: Pyroxenes are zoned from augite cores (En_45.3Wo_25.6, FeO/MnO = 28.5) and pigeonite cores (En_40.3Wo_19.6 FeO/MnO = 32.3) to ferropigeonite rims (En_8.4Wo_14.5 FeO/MnO = 41.1). Plagioclase is characterized by homogeneous compositions of An₅₂ Or_1.4. Titanomagnetite (TiO₂ 29.4 wt%, FeO 65.5 wt%, Al₂O₃ 1.3 wt%); ilmenite (TiO₂ 48.9 wt%, FeO 49.8 wt%).