Classification: Basaltic Achondrite (Eucrite)
Explainer: This means that the sample is from an asteroid parent body, which is differentiated. It is a specific type of achondrite meteorite called eucrites. The eucrites are rich in ferrosilite (iron-rich phase) pyroxenes and in anorthite (calcium-rich phase ) plagioclase. They are also strongly linked with the diogenites and the howardites. The howardites, eucrites and diogenites are collectively referred to as the HED meteorites. They’re compositionally similar to the second largest known asteroid in the solar system, 4 Vesta and has been proposed as the most likely candidate for the source of eucrites. You can see more about where this sample fits into the meteorite classification scheme by looking at this page.
Description: Taken from the Meteoritical Bulletin for HUT 18035
History: The meteorite was recovered as part of the Lost Meteorites of Antarctica project, which was funded in the UK by the Leverhulme Trust and supported by the British Antarctic Survey and the University of Manchester. These samples were collected as part of the project’s first field season in austral summer December 2018 – January 2019 by a two person field party consisting of Katherine Joy and Julie Baum. Found on blue ice surface. Altitude 1269 m.
Physical characteristics: Mass: 1.66 g. Pieces: 1. Dimensions: 1.5 × 1.5 × 1 cm. An irregular, part stone with 40% shiny black fusion crust on two sides and sandy colored interior with white clasts.
Petrography: Brecciated composed of fragmented pyroxene and plagioclase grains, as well as granular igneous clasts comprised of pyroxene and plagioclase with a granular texture. Main minerals are pyroxene (up to 0.6 mm) with ubiquitous exsolution lamellae, and plagioclase (up to 0.7 mm). Minor silica, ilmenite, phosphate and chromite are present.
Mineral compositions and geochemistry: All analyses by EPMA. Orthopyroxene Fs61.3±1.1Wo3.9±1.3 (N=44), clinopyroxene Fs33.6±5.3Wo36.6±6.1 (N=97). All pyroxene combined Fs42.2±13.7Wo26.4±16.1 (N=141). Plagioclase An86.8±1.5Ab12.6±1.5 (N=31). Average Fe/Mn (atomic) in orthopyroxene = 30.3±0.9 (N=44). Compositional ranges indicate this is a basaltic eucrite. Oxygen Isotopes (J. Malley, R. Greenwood and R. Findlay, OU): One fragment was analyzed for oxygen isotopes by laser fluorination at OU. An ~18 mg homogenized sample yielded the following results (per mil deviation from VSMOW): δ17O=1.598, δ18O=3.485, Δ17O=-0.229. Δ17O value calculated using the linearized method of Miller (2002), with a slope value of 0.5247. This plots within ± 2? field for the HEDs as defined by Greenwood et al. (2017).
Specimens: 1.389 g type specimen (main mass) held at NHM.
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