NWA 17920 CK6 Carbonaceous Chondrite Meteorite End Cut, Main Mass with Primary Fusion Crust, 279.83g

The main mass of NWA 17920, a CK6 carbonaceous chondrite

NWA 17920 is classified as CK6 in the Meteoritical Bulletin, approved 26 February 2026. The Bulletin records the main mass as being with Brian McDonald, and this end cut is that main mass. It weighs 279.83g and retains primary fusion crust across part of its exterior, with a single cut face exposing the interior. The photographs show the exact specimen offered.

Structure and features

The cut face shows a pale olive-grey recrystallized matrix crossed by fractures, with darker zones where the texture becomes visibly clast-rich. Chondrules are present but indistinct, which is the expected appearance for petrologic type 6, where thermal metamorphism has largely erased the original chondrule outlines. The Bulletin describes the meteorite as a strongly fractured rock with chondritic texture and hardly recognizable chondrules. Several rounded chondrules roughly a millimetre across are visible in the macro images, some carrying rust-toned rims. Part of the exterior retains primary fusion crust; the remainder is weathered exterior surface.

Published petrography by Jose Garcia at ADARA describes chondrules up to 1192±299 micrometers in diameter (n=12) set in an abundant recrystallized matrix dominated by olivine, with pyroxene, plagioclase and magnetite. Feldspar grain size is 98±42 micrometers (n=36).

Published geochemistry from MB 115: olivine Fa32.2±1.9 with NiO 0.5±0.1 wt% (n=10); low-Ca pyroxene Fs28.6±1.8Wo3.4±2.8 (n=4); Ca-bearing pyroxene Fs10.2±2.3Wo43.6±3.1 (n=5); plagioclase An36.9±2.1 (n=14); magnetite with Cr2O3 at 3.1±0.4 wt%. The Bulletin records a shock stage of moderate, a weathering grade of low, and a magnetic susceptibility of 4.61. The classification as CK6 is based on the petrographic type of the chondrules, the feldspar grain size, and the mineral composition.

Discovery and provenance

NWA 17920 was found in 2025 in Mali. The Bulletin records a total known weight of 433.1g recovered as a single piece. The finder is recorded as anonymous. The type specimen, 21.20g, is held at MUNA, the Museo de la Naturaleza y Arqueologia in Santa Cruz de Tenerife, Spain. Three thin sections are held at ADARA. The main mass is recorded as being with Brian McDonald of Treasure Coast Meteorite Co. Classification was carried out by J. Garcia at ADARA and approved 26 February 2026. The working name recorded in the Bulletin is BMD 021, and one of the photographs shows the specimen with that working name label.

Because the meteorite was recovered as a single 433.1g stone, this 279.83g end cut is the largest surviving portion of that stone after the type specimen and the cut material were removed.

Scientific context

As of August 2026 the Meteoritical Bulletin database records 108 approved meteorites classified as CK6. CK chondrites are a group within the carbonaceous chondrites, distinguished by high olivine content, abundant magnetite, and a generally oxidized mineralogy. The CK group is unusual among carbonaceous chondrites in that it includes strongly thermally metamorphosed members, of which type 6 is the most metamorphosed commonly recognized.

In a type 6 CK chondrite the matrix has recrystallized and the chondrules have been substantially equilibrated with their surroundings, which is why the Bulletin describes them here as hardly recognizable. The feldspar grain size of 98 micrometers is one of the measurements used to assign that petrologic type. Further background is available in our carbonaceous chondrite collection.

Frequently asked questions

Is NWA 17920 officially classified? Yes. It is an officially named meteorite classified as CK6, approved by the Meteoritical Society on 26 February 2026. Its writeup appears in Meteoritical Bulletin 115, which is in preparation and has not yet been published as a volume. Offered by Treasure Coast Meteorite Co., IMCA #3323.

What does main mass mean? The main mass is the largest single remaining piece of a given meteorite. The Meteoritical Bulletin records the main mass of NWA 17920 as being with Brian McDonald, and this specimen is that mass.

What is primary fusion crust? Primary fusion crust is the glassy skin formed on the outside of a meteorite as it ablates during atmospheric entry. It survives on part of this specimen's exterior. Surfaces created later, by fragmentation or by cutting, do not carry it.

What does CK6 mean? CK identifies the chemical group, a carbonaceous chondrite group named for the Karoonda meteorite. The 6 is the petrologic type, indicating extensive thermal metamorphism on the parent body, to the point where chondrule outlines are difficult to distinguish.

How does this relate to the NWA 17920 slice you list? Both come from the same single 433.1g stone. The slice is a full cross-section cut from it; this specimen is the main mass that remains.

Collector significance

This is the main mass of the meteorite, the largest surviving piece of a stone that the Bulletin records as having been recovered whole at 433.1g. It carries primary fusion crust on part of its exterior and a cut face that exposes the recrystallized interior, so both the entry surface and the internal texture are present in a single specimen. As of August 2026 the database records 108 approved CK6 meteorites.

This specimen carries serial TC-00034 in the Treasure Coast Meteorite Co. specimen record programme. Its permanent record, with identification data, provenance and photographs, is at Specimen Record TC-00034, and the full index is on the specimen registry.

Browse the full Carbonaceous Chondrites collection, including the NWA 17920 full slice cut from this same stone.

Meteoritical Bulletin entry: Northwest Africa 17920 | Classification: CK6 | Find, Mali, 2025 | TKW 433.1g | MB 115, in preparation | IMCA #3323