NWA 17916 CO3 Carbonaceous Chondrite Meteorite Slice, 13.67g, Dense Chondrule Population

Chondrule density in primitive matrix

This 13.67-gram slice reveals the characteristic structure of CO3 carbonaceous chondrites: small, tightly packed chondrules suspended in a fine-grained matrix. The slice format provides direct visual access to dozens of individual chondrules, each representing a discrete melting event in the solar nebula. The dark matrix material contains the same volatile-rich compounds and presolar grains that make CO chondrites essential to understanding early solar system chemistry.

The slice measures substantial enough for detailed examination while remaining accessible for collectors building primitive meteorite reference collections. Surface preparation reveals chondrule boundaries and matrix texture without obscuring the specimen's natural composition.

Structure and features

CO chondrites derive their designation from the type specimen that fell in Ornans, France in 1868. This group exhibits the smallest average chondrule size among ordinary chondrites, typically 150 micrometers in diameter, creating the dense packing visible throughout this slice. The Type 3 petrologic grade confirms minimal thermal alteration since accretion, meaning the minerals and organic compounds present retain their original nebular states.

Refractory calcium-aluminum-rich inclusions (CAIs) appear as lighter-toned irregular shapes within the matrix. These inclusions formed at temperatures exceeding 1,300°C in the innermost regions of the protoplanetary disk before being transported outward and incorporated into the parent asteroid. The matrix itself contains phyllosilicates, magnetite, and organic compounds that formed at much lower temperatures, demonstrating the heterogeneous mixing that characterized the early solar nebula.

Scientific context

CO chondrites formed in the outer asteroid belt approximately 4.567 billion years ago, capturing a mixture of high-temperature condensates and low-temperature ices and organics. The parent body accreted quickly enough to avoid significant heating from radioactive decay, preserving the primitive composition. This makes CO3 specimens like NWA 17916 critical for understanding the chemical and isotopic inventory available during planet formation.

Studies of CO chondrites have identified presolar silicon carbide and graphite grains—literal stardust older than the solar system itself—embedded in the matrix. The organic compounds include amino acids and polycyclic aromatic hydrocarbons that may have seeded early Earth with prebiotic chemistry. Learn About Meteorites to explore how these primitive specimens inform planetary science research.

Frequently asked questions

Is this meteorite authenticated? Yes. NWA 17916 is classified as CO3 in the Meteoritical Bulletin. You can verify the classification here: NWA 17916. Each specimen includes a certificate of authenticity documenting the classification and specimen weight.

What does Type 3 mean for a chondrite? The number indicates petrologic type on a scale from 3 (unaltered) to 6 (heavily metamorphosed). Type 3 specimens experienced minimal heating after formation, preserving volatile elements, water-bearing minerals, and organic compounds that would have been destroyed at higher temperatures. This makes them the most scientifically valuable for studying original nebular composition.

What is included with this specimen? The 13.67g slice and a certificate of authenticity documenting the meteorite name, classification, weight, and origin. No display stand is included.

Why are CO chondrites darker than ordinary chondrites? The dark coloration results from the carbon-rich matrix, which contains several percent organic matter and fine-grained opaques including magnetite and iron sulfides. This volatile-rich composition distinguishes carbonaceous chondrites from the more oxidized ordinary chondrite groups.

Reference material for primitive meteorite study

CO chondrites represent approximately 1% of observed meteorite falls, making them considerably less common than ordinary chondrites in collections. The combination of small chondrule size, abundant CAIs, and preserved organics makes them particularly valued by institutions and private collectors focused on early solar system materials. This 13.67-gram slice provides sufficient size for both display and comparative study without the investment required for larger specimens.

The piece displays well from either side, allowing collectors to showcase the chondrule population regardless of orientation. The slice format offers more accessible pricing than complete individuals while preserving the full scientific characteristics that define the group. Explore additional primitive specimens in our Carbonaceous Chondrites collection.

Meteoritical Bulletin entry: NWA 17916 | Classification: CO3 | Find, Algeria, 2025