Bir Ounane 001 Primitive Achondrite Meteorite End Cut, Achondrite-prim, 70.22g, Mirror Polished Face

Bir Ounane 001, a 70.22 gram polished end cut

This end cut of Bir Ounane 001 keeps one natural exterior surface and exposes a mirror polished interior face of 70.22 g. The Meteoritical Bulletin classifies Bir Ounane 001 as a primitive achondrite (Achondrite-prim), a meteorite that was heated and recrystallized on its parent body without fully separating into a core and a crust. Its writeup calls it an olivine websterite, and its mineral chemistry does not match any established group.

One of 16 approved meteorites classified as Achondrite-prim, as recorded in the Meteoritical Bulletin database in September 2026. That is a count of database entries rather than separate falls: the Bulletin entry for Northwest Africa 15061 records it as likely paired with Bir Ounane 001.

Surface and features

The cut face is polished to a mirror finish and has not been coated or sealed. Against the gray groundmass the metal reads as bright silver flecks scattered across the whole face, with fine pale veinlets running between them. The Bulletin describes numerous oxidized crosscutting veinlets throughout the meteorite, and those are what the veining on this face shows. A natural break runs across the lower part of the face, and the back and sides keep the weathered brown exterior of the stone.

Under close light the polish holds a clean reflection, so the granoblastic texture described in the Bulletin can be read directly: tightly interlocking silicate grains, most of them under half a millimeter, rather than the round chondrules of a chondrite.

Discovery and provenance

According to the Meteoritical Bulletin, Bir Ounane 001 was found in 2022 by Sahrawi meteorite hunters roughly 118 km southeast of Taoudenni in the Gao region of Mali, with the locality of Bir Ounane about 84 km southwest of the find site. Multiple identical appearing stones were recovered, totalling 80 kg, the largest weighing 9,883 g.

The meteorite was classified by A. Ross and C. Agee at the University of New Mexico, with oxygen isotope analysis by K. Ziegler at the same institution. It was approved on 11 December 2022 and published in Meteoritical Bulletin 111 (2023). The Bulletin records 109.3 g on deposit at UNM and the main mass with Bachir Salek. This end cut was acquired by Treasure Coast Meteorite Co.

Scientific context

Primitive achondrites sit between the chondrites and the fully differentiated achondrites. Their parent bodies were heated enough to recrystallize and begin melting, but not enough to separate metal from rock completely, so they keep a composition close to their chondritic starting material while losing the chondrules that would identify them as chondrites.

The Bulletin records Bir Ounane 001 as an olivine websterite made of forsterite (30 to 40 percent), enstatite (40 to 50 percent), diopside (10 to 20 percent) and andesine plagioclase (5 to 10 percent), with kamacite and oxidized iron at 5 to 10 percent and minor troilite, daubreelite and schreibersite.

Its classification is a puzzle worth stating plainly, because the Bulletin itself sets it out. The magnesian silicates and the daubreelite resemble winonaites. The metal abundance resembles acapulcoites and lodranites. The fine grain size fits winonaites or acapulcoites but not lodranites. The oxygen isotope value Delta-17O is consistent with acapulcoites and lodranites, while its delta-18O is higher than the usual range for those groups, and the triple oxygen isotope values are unlike winonaites. No established group accounts for all of it, which is why the Bulletin classifies it as a primitive achondrite not belonging to a known group. More on how these classifications are decided is set out in understanding the Meteoritical Bulletin.

Frequently asked questions

What is a primitive achondrite? A meteorite whose parent body was heated and recrystallized, and began to melt, without separating fully into layers. It keeps a near-chondritic composition but has lost its chondrules.

Why is it called ungrouped? Its mineralogy and oxygen isotopes do not match any established group. The Bulletin classifies it as a primitive achondrite not belonging to a known group, and its writeup compares it with winonaites, acapulcoites and lodranites without placing it in any of them.

Has the face been coated or treated? No. The polished face is bare metal and silicate, with no coating, sealant or wax.

How many meteorites like this are known? The Meteoritical Bulletin database lists 16 approved Achondrite-prim entries as of September 2026. Pairing matters here: the entry for Northwest Africa 15061 records it as likely paired with Bir Ounane 001, so the number of separate falls is smaller than the entry count.

How do I know it is what it says? The classification can be checked directly in the Meteoritical Bulletin Database entry for Bir Ounane 001. Treasure Coast Meteorite Co. is IMCA Member #3323.

Collector significance

An end cut gives both halves of the story in one piece: the weathered exterior the stone arrived with, and a polished interior face showing the texture and metal that classification is based on. At 70.22 g this is a substantial piece of a meteorite with no group of its own, from a total recorded mass of 80 kg. Browse more in the primitive achondrite collection, or see the ungrouped achondrites.

Classification data from the Meteoritical Bulletin entry for Bir Ounane 001. Treasure Coast Meteorite Co., IMCA Member #3323.