{"product_id":"ksar-ghilane-022-1-75g-ungrouped-achondrite-meteorite-slice","title":"Ksar Ghilane 022 Ungrouped Achondrite Meteorite Slice, Achondrite-ung, 1.75g, Augite-Rich Matrix","description":"\u003ch2\u003eDifferentiated material from an unknown parent body\u003c\/h2\u003e\n\u003cp\u003eThis 1.75g slice exposes a cross-section of augite-dominant matrix representing differentiated planetary crust that does not match any established achondrite group. The specimen preserves an equant crystal texture where individual augite grains average 1.5 mm across, creating a granular fabric visible throughout the slice. Minor enstatite appears interspersed among the pyroxene grains, alongside accessory phases including chromium-bearing troilite, daubreelite, alabandite, and manganese-iron oxide. Secondary calcite veining crosses portions of the matrix, recording post-formation aqueous alteration.\u003c\/p\u003e\n\u003cp\u003eThe slice format allows observation of the textural relationships between mineral phases and provides a representative sample of the meteorite's internal structure. Found in Tunisia in 2023, this specimen joined the small inventory of ungrouped achondrites that challenge existing classification frameworks.\u003c\/p\u003e\n\u003ch2\u003ePyroxene-dominated texture and mineralogy\u003c\/h2\u003e\n\u003cp\u003eAugite forms the primary mineral phase throughout this specimen, characterized by a ferrosilite content near zero (Fs ~0.0-0.1) and wollastonite component ranging from Wo ~39.4 to 42.3. These compositional values place the pyroxene in the calcic field, consistent with crystallization from a basaltic melt under conditions similar to those that produce terrestrial gabbros. The equant grain morphology indicates slow cooling rates that allowed crystals to develop isometric shapes rather than elongated or skeletal forms.\u003c\/p\u003e\n\u003cp\u003eEnstatite occurs as a minor phase with ferrosilite content near Fs ~0.1 and wollastonite ranging from Wo ~0.9 to 3.6, representing orthopyroxene that crystallized alongside the augite. Sulfide minerals include chromium-enriched troilite and daubreelite, both of which typically form during late-stage crystallization in reduced environments. Alabandite (manganese sulfide) and the manganese-iron oxide phase represent additional accessory minerals that record the availability of manganese during parent body differentiation.\u003c\/p\u003e\n\u003ch2\u003eScientific context\u003c\/h2\u003e\n\u003cp\u003eUngrouped achondrites represent meteorites that experienced complete melting and differentiation on their parent asteroids but do not share the diagnostic characteristics of established groups like HEDs, angrites, or aubrites. Each ungrouped specimen potentially samples a distinct parent body with its own thermal and compositional history. Ksar Ghilane 022's augite-rich composition and specific pyroxene chemistry distinguish it from all currently recognized achondrite families, suggesting formation on a previously unsampled differentiated asteroid.\u003c\/p\u003e\n\u003cp\u003eOxygen isotope analyses of acid-washed subsamples place this meteorite on a distinct trajectory in three-isotope space, further confirming its independent origin. The crystallization sequence preserved in this specimen, augite as the primary phase with minor orthopyroxene, indicates a basaltic composition similar to eucrites but with mineralogical and chemical signatures that prevent classification within the HED suite. Understanding the diversity of differentiated asteroids requires specimens like Ksar Ghilane 022 that expand our knowledge beyond well-studied groups. Learn more about meteorite classification and origins at \u003ca href=\"\/pages\/learn-about-meteorites\"\u003eLearn About Meteorites\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eWhat the research reports\u003c\/h2\u003e\n\u003cp\u003eThe Meteoritical Bulletin classifies Ksar Ghilane 022 as an ungrouped achondrite (Achondrite-ung), published in Meteoritical Bulletin 113 (2025). The writeup, by A. Irving and P. Carpenter, describes a rock made mostly (more than 90 percent by volume) of nearly iron-free augite, with minor enstatite and unusual sulfides, from a find in Tunisia in 2023 with a total recorded mass of 50 kg. The research below comes from the authors’ own samples and methods and is given here as the study states it.\u003c\/p\u003e\n\u003ch3\u003eRider-Stokes et al. (2025): a Mercury analog, not a proven Mercury meteorite\u003c\/h3\u003e\n\u003cp\u003eB. G. Rider-Stokes, E. Branagan-Harris, K. Markus, J. F. Snape, S. L. Jackson, S. S. Russell, R. C. Greenwood, T. H. Burbine, M. J. Whitehouse, D. A. Rothery, L. F. White and M. M. Grady published \u003ca href=\"https:\/\/doi.org\/10.1016\/j.icarus.2025.116713\" rel=\"noopener\" target=\"_blank\"\u003eInsights into pyroxene-dominated surfaces and implications for ongoing space exploration missions\u003c\/a\u003e (Icarus, volume 441, article 116713, 2025). The lead author is at The Open University. The study examined Ksar Ghilane 022 alongside Northwest Africa 15915, which appears to be related. Both contain iron-free silicates and unusual sulfides such as oldhamite, have oxygen isotope compositions in the field of the enstatite chondrites and aubrites, show almost no spectral features in visible and near-infrared light, and have a mineralogy similar to what is expected for the surface of Mercury.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat the authors concluded.\u003c\/strong\u003e The paper does not claim these rocks came from Mercury. Its abstract states that “it is unlikely that the two meteorites are fragments of Mercury,” while suggesting they may be good analogs for Mercury’s surface on a regional scale, useful for comparison with data from the ESA and JAXA BepiColombo mission. News coverage in 2025 described them as possible Mercury meteorites. In an \u003ca href=\"https:\/\/www.open.ac.uk\/blogs\/news\/science-mct\/ou-researcher-helps-to-solve-the-mystery-of-mercurys-missing-meteorites\/\" rel=\"noopener\" target=\"_blank\"\u003eOpen University news release\u003c\/a\u003e, the lead author noted clear differences from Mercury, including infrared data, plagioclase content and age, while adding that a Mercurian origin cannot be ruled out.\u003c\/p\u003e\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eIs this meteorite authenticated?\u003c\/strong\u003e Ksar Ghilane 022 is classified in the Meteoritical Bulletin as Achondrite-ung. You can verify the classification at \u003ca href=\"https:\/\/www.lpi.usra.edu\/meteor\/metbull.php?sea=Ksar%20Ghilane%20022\u0026amp;sfor=names\" rel=\"noopener\" target=\"_blank\"\u003eMeteoritical Bulletin: Ksar Ghilane 022\u003c\/a\u003e. This specimen includes a certificate of authenticity documenting its provenance and classification.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does \"ungrouped achondrite\" mean?\u003c\/strong\u003e An ungrouped achondrite is differentiated igneous rock from an asteroid that does not match the mineralogy, chemistry, or oxygen isotope signature of any established achondrite group. Each ungrouped specimen potentially represents material from a distinct parent body.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is included with this specimen?\u003c\/strong\u003e This listing includes the 1.75g meteorite slice and certificate of authenticity. No display stand is included.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhy are augite crystals significant in this meteorite?\u003c\/strong\u003e The dominance of augite with near-zero ferrosilite content indicates crystallization from a calcium-rich basaltic melt under reducing conditions. This mineral assemblage differs from the augite chemistry in HED meteorites and other achondrite groups, supporting the specimen's ungrouped status.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat caused the calcite veining?\u003c\/strong\u003e Secondary calcite veins form when aqueous fluids carrying dissolved calcium carbonate infiltrate fractures in the meteorite, typically during terrestrial weathering after the fall or find. These veins postdate the original igneous crystallization of the rock.\u003c\/p\u003e\n\u003ch2\u003eCollector significance\u003c\/h2\u003e\n\u003cp\u003eUngrouped achondrites occupy a specialized niche in collections because each specimen potentially represents a differentiated parent body not sampled by any established group. With only a small number of ungrouped achondrites recognized in the Meteoritical Bulletin, these specimens document asteroidal diversity beyond the major achondrite groups. This 1.75g slice provides accessible entry into this scientifically significant category at a weight suitable for study collections and educational displays.\u003c\/p\u003e\n\u003cp\u003eThe slice format exposes the augite-dominated texture and allows direct observation of the mineralogical features described in the classification documentation. For collectors building representative suites of differentiated meteorites, Ksar Ghilane 022 fills the ungrouped achondrite position with material that cannot be approximated by specimens from established groups. Browse additional differentiated meteorite types in our \u003ca href=\"\/collections\/ungrouped-achondrites\"\u003eUngrouped Achondrites\u003c\/a\u003e collection.\u003c\/p\u003e\n\u003cp\u003eMeteoritical Bulletin entry: \u003ca href=\"https:\/\/www.lpi.usra.edu\/meteor\/metbull.php?sea=Ksar%20Ghilane%20022\u0026amp;sfor=names\" rel=\"noopener\" target=\"_blank\"\u003eKsar Ghilane 022\u003c\/a\u003e | Classification: Achondrite-ung | Find, Tunisia, 2023\u003c\/p\u003e","brand":"Treasure Coast Meteorite Co.","offers":[{"title":"Default Title","offer_id":44863852904495,"sku":"KSAR-GHILANE-022-1.75G-SLICE","price":90.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0726\/9724\/9839\/files\/ksar-ghilane-022-achondrite-meteorite-slice-capsule-1-75g.heic?v=1779460587","url":"https:\/\/www.tcmeteorites.com\/products\/ksar-ghilane-022-1-75g-ungrouped-achondrite-meteorite-slice","provider":"Treasure Coast Meteorite Co.","version":"1.0","type":"link"}