Characterizing and Determining the Appropriate Classification of Meteorite NWA 725

Session: 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

Presenting Author:

Authors:

Abstract:

Meteorites appear in many environments on Earth, but most commonly in deserts, as they are easier to find. There are many different types of meteorites, each varying in specific classifications. The main ones are iron, stony, and stony-iron. The meteorite NWA 725 is classified as a primitive stony meteorite and has undergone classification name switches over the years since its discovery in 2000, from acapulcoite to winonaite.

The reason for the uncertainty of the classification is due to its mineral and geochemical compositional data. To better understand the classification of NWA 725, we conducted a detailed petrographic and compositional analysis. This included the creation of a thin section map, polarized light microscopy (PPL and XPL) to examine relict chondrules, and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) to determine mineral and elemental compositions.

Our analysis revealed the presence of Mg-rich olivine (forsterite), minor fayalite, augite, trace troilite, and unusually high chromium levels compared to previously published studies. Our findings concluded that NWA 725 was well within the acapulcoite trend based on its olivine Fa% and FeO/MnO values. Additionally, our measured chromite compositions (Cr = 0.92; Mg = 0.50) further support the classification as an acapulcoite. These results, supported by comparison with literature data, suggest that NWA 725 is best categorized as an acapulcoite. Future research will involve secondary analysis and additional data collection to confirm and refine this classification.