Ksar Ghilane 022 Ungrouped Achondrite Meteorite Slice, achondrite-ung, 2.11g, Augite-Rich Differentiated Material

Augite-dominated achondrite from an unidentified differentiated body

This 2.11g slice presents a texture dominated by equant augite crystals averaging 1.5 mm in size, creating a coarse-grained mosaic visible across the cut surface. Minor enstatite appears alongside accessory phases including chromium-bearing troilite, daubreelite, alabandite, and a manganese-iron oxide assemblage. Secondary calcite veins traverse portions of the slice, recording post-crystallization alteration. The specimen represents differentiated planetary material that underwent complete melting and slow crystallization within a parent body's interior, yet its mineral chemistry and oxygen isotope signature do not match any established achondrite group.

Ksar Ghilane 022 was recovered from the Tunisian desert in 2023 and classified as an ungrouped achondrite based on petrographic analysis and geochemical data. The meteorite's classification reflects the fact that its composition places it outside known achondrite families, making each specimen a reference sample for comparative planetology studies. This slice preserves the original igneous texture formed during slow cooling within a differentiated asteroid.

Pyroxene mineralogy and accessory phases

The augite component shows ferroan silite values near zero (Fs ~0.0-0.1) with wollastonite content between 39.4 and 42.3, indicating calcium-rich clinopyroxene that crystallized from a basaltic melt. The subordinate enstatite phase displays similarly low iron content (Fs ~0.1) but minimal calcium (Wo ~0.9-3.6), representing orthopyroxene that formed alongside the dominant augite. This dual-pyroxene assemblage records crystallization conditions distinct from eucrites, angrites, and other common basaltic achondrites.

Chromium-bearing troilite and daubreelite occur as accessory sulfides, while alabandite (manganese sulfide) adds to the meteorite's trace mineral inventory. The presence of an Mn-Fe oxide phase further distinguishes this material from typical basaltic achondrites. These accessory minerals provide constraints on oxygen fugacity and sulfur activity during crystallization, offering geochemical fingerprints that separate Ksar Ghilane 022 from established achondrite groups.

Differentiated asteroid origins and classification challenges

Achondrites form through igneous processes on differentiated parent bodies where internal heating caused complete melting and subsequent crystallization. Ksar Ghilane 022's coarse pyroxene texture indicates it crystallized slowly at depth within such a body, likely as part of a cumulate pile or shallow intrusion. Oxygen isotope analyses of acid-washed subsamples have been performed but plot outside the fields of known achondrite groups, supporting the ungrouped classification assigned by the Meteoritical Bulletin.

The meteorite likely originated from a small differentiated asteroid that experienced early melting during the first few million years of solar system history. Its parent body remains unidentified and may represent one of the countless asteroids disrupted by collisions over the past 4.5 billion years. Materials like Ksar Ghilane 022 expand our understanding of the diversity of differentiated bodies that formed in the early solar system, demonstrating that not all basaltic crusts and mantles followed the same evolutionary path. Learn About Meteorites to explore how scientists classify specimens based on mineralogy and chemistry.

Frequently asked questions

Is this meteorite authenticated? Yes. Ksar Ghilane 022 is classified in the Meteoritical Bulletin as achondrite-ung based on petrographic and geochemical analysis. View the official entry here: Ksar Ghilane 022. This specimen includes a certificate of authenticity with your purchase.

What does ungrouped achondrite mean? Ungrouped achondrites are differentiated meteorites that do not fit into established classification schemes like eucrites, angrites, or aubrites. Ksar Ghilane 022's mineral chemistry and oxygen isotopes place it outside all known groups, indicating it came from a distinct parent body not represented in other meteorite collections.

What is included with this specimen? You receive the 2.11g slice shown in the photographs and a certificate of authenticity. No display stand is included unless specifically noted in the product listing.

Why are augite-rich achondrites scientifically significant? Clinopyroxene-dominated achondrites like Ksar Ghilane 022 sample igneous processes on small differentiated bodies. Their mineral assemblages record cooling rates, crystallization sequences, and mantle compositions that differ from Earth and larger planetary bodies, providing comparative data for understanding early solar system differentiation.

How should I store and handle this slice? Store in a dry environment away from humidity to prevent alteration of sulfide phases and secondary minerals. Handle by the edges to avoid transferring oils to the cut surface. The polished face can be gently cleaned with a soft, dry cloth if dust accumulates.

Ungrouped achondrites in meteorite collections

Collectors pursuing Ungrouped Achondrites acquire specimens that represent unsampled parent bodies, effectively holding material from asteroids not otherwise represented in terrestrial collections. Ksar Ghilane 022's recent classification and limited distribution make it a timely addition for collectors building comprehensive achondrite suites. The specimen's coarse augite texture provides visual interest under magnification, while its scientific orphan status adds research value.

This 2.11g slice offers accessible entry into ungrouped achondrite collecting without requiring significant display space. The size allows for detailed examination of pyroxene grain boundaries and accessory phases while remaining suitable for standard collection storage. As additional Ksar Ghilane 022 material reaches classification and distribution, early acquisition secures representation of this geochemically distinct fall before availability narrows.

Meteoritical Bulletin entry: Ksar Ghilane 022 | Classification: achondrite-ung | Find, Tunisia, 2023