How to Read a Meteoritical Bulletin Entry

April 24, 2026

Top view of Guemar 002, an unbrecciated lunar mare basalt meteorite

Buyer's Guide

Every authentic classified meteorite has a permanent record in the Meteoritical Bulletin, the official global registry maintained by the Meteoritical Society. This guide explains what each field means, what to look for, and how to use the Bulletin as an independent verification tool before you buy anything from anyone.

The database is publicly accessible at lpi.usra.edu. No login required. If a seller claims a meteorite is classified, you can look it up yourself in under a minute.

What the Meteoritical Bulletin Is

The Meteoritical Bulletin is the peer-reviewed record of approved meteorites published by the Meteoritical Society, the international scientific body that oversees meteorite classification. Each entry is approved by a committee of scientists after a classifier submits petrographic analysis, geochemical data, and provenance documentation. An entry in the Bulletin means the specimen has been physically analyzed in a laboratory and formally accepted as a meteorite of a specific type.

Entries are organized by issue number. MB 114, for example, refers to the 114th issue. Each new issue approves a batch of newly classified specimens from around the world. The database currently contains over 70,000 approved entries.

What the Bulletin does and does not certify

The Bulletin certifies that a meteorite of a specific name and classification exists and has been analyzed in a laboratory. It does not certify any individual specimen you might purchase. A certificate of authenticity from a reputable dealer connects your specific piece to that record. Both together constitute verified provenance.

To understand more about how classification works, see our guide to how meteorites are classified.

Anatomy of a Meteoritical Bulletin Entry

The following walkthrough covers every major field using a real entry as the example: Guemar 002, a lunar basalt recovered from Algeria in 2023 and approved in MB 114.

Meteoritical Bulletin entry heading for Guemar 002 showing name, classification, and top-level fields

The heading section of a Meteoritical Bulletin entry for Guemar 002. The top fields establish the specimen's identity, recovery context, and total known mass.

Identity and recovery fields

Name

The official name assigned by the Meteoritical Society, derived from the recovery location. Names are permanent and cannot be changed after approval. NWA meteorites were recovered somewhere in Northwest Africa. Named localities like Guemar, Adrar, or Tissint refer to specific places in the country of recovery.

Abbreviation

The shorthand used in scientific literature. NWA meteorites carry their number as the abbreviation (NWA 17472). Named locality meteorites may have no abbreviation if the full name is short enough.

Observed fall / Year found

An observed fall means someone witnessed the meteorite enter the atmosphere and land. These are scientifically exceptional because they can be recovered before terrestrial weathering begins. A find means the meteorite was discovered on the ground with no witnessed fall event. The vast majority of classified meteorites are finds. Find year refers to when the specimen was recovered or purchased, not when it fell.

Country

The country of recovery. For NWA meteorites, this is listed as Northwest Africa in parentheses, indicating the recovery location is known only to the region. Many NWA specimens are purchased from dealers in Morocco, Algeria, or Mauritania but their precise find location is undocumented.

Mass

The total known mass of all material associated with this meteorite name, not the mass of any individual piece you might purchase. For Guemar 002, total mass is 195.61g across four stones. A meteorite with a total known mass of 50g is in a fundamentally different rarity category from one with 50 kilograms.

Meteoritical Bulletin entry writeup section for Guemar 002 showing history, classification, and physical characteristics

The writeup section of the entry, covering history, physical characteristics, and the beginning of the scientific analysis fields.

Scientific classification fields

Classification

The scientific type of the meteorite, following a hierarchical system. At the broadest level: chondrites (primitive, undifferentiated), achondrites (from differentiated parent bodies), stony-irons, and irons. Further subdivisions identify parent body, chemical group, and petrologic type. Lunar (basalt) means Moon rock preserving primary igneous texture. Martian (Shergottite) means Mars, basaltic group. L5 ordinary chondrite means low-iron group at petrologic type 5, indicating moderate thermal metamorphism. Each classification carries specific scientific meaning about origin and history.

MB issue and approval date

The issue number and date the classification was formally accepted. For Guemar 002 this is MB 114, approved July 25, 2025. Material sold before the approval date cannot have been sold as a classified specimen under that name. If a seller claims to have sold a specimen years before its Bulletin approval date, that is a red flag.

History

The provenance narrative. This field documents how the meteorite was found or purchased and how it moved from recovery to classification. It names dealers, collectors, and institutions in the chain of custody. For Guemar 002, the history traces four stones through several African dealers to a lot purchase in September 2024, then records which stones went to which collectors. This is what separates a well-provenanced specimen from an anonymous purchase.

Physical characteristics

A brief description of the meteorite's exterior: fusion crust presence or absence, color, texture, and any distinctive surface features. This is the visual record that connects the scientific analysis to the physical object.

Petrography

Microscopic analysis of the rock's internal structure: minerals present, grain sizes, textures, and relationships to each other. Maskelynite in a Martian shergottite indicates hypervelocity shock during ejection from Mars. Sub-ophitic texture in a lunar basalt indicates slow magma cooling. Flow banding in a lunar melt breccia records the impact that created it. Each petrographic detail is a data point in the rock's history.

Geochemistry

Quantitative chemical analysis of the major mineral phases by electron microprobe or SEM-EDS. Olivine compositions are given as fayalite mole percent (Fa). Pyroxene uses ferrosilite (Fs) and wollastonite (Wo) values. Plagioclase is expressed as anorthite content (An). These numbers confirm the classification and provide a permanent chemical fingerprint for future research. Lunar basalts have characteristic FeO/MnO ratios that are distinct from terrestrial rocks and Martian rocks.

The data section of the entry, showing geochemical analysis, classifier information, type specimen details, and weathering and shock condition grades.

Provenance and condition fields

Classifier and institution

The scientist or team who performed the analysis and the institution where the work was done. Cascadia Meteorite Laboratory at Portland State University, the Institute of Meteoritics at the University of New Mexico, and the Museum für Naturkunde in Berlin are among the most active classifiers in the current database. The classifier's name and affiliation are part of the permanent scientific record.

Type specimen

The portion of the meteorite held by the classifying institution as a permanent reference sample, retained in perpetuity for future scientific study. Its mass and location confirm that a physical sample exists in an institutional collection, one of the requirements for Bulletin approval. For Guemar 002, 20.1g is held at Cascadia. The type specimen cannot be sold.

Main mass holder

Who holds the largest portion of the total recovered material. For commercially significant meteorites, the main mass is often held by a private collector or dealer. This field gives context for where the bulk of available material originates.

Shock stage

A standardized measure of the shock pressure the meteorite experienced, expressed on a scale from S1 (unshocked) to S6 (very strongly shocked). High shock stages are expected in ejected planetary material. A Martian meteorite with a low shock stage would raise scientific questions, since escape from Mars requires hypervelocity impact. Determined from petrographic indicators including plagioclase conversion to maskelynite and melt pocket distribution.

Weathering grade

How much terrestrial alteration the meteorite has experienced since landing. Expressed on a scale from W0 (fresh) to W6 (heavily weathered). Low grades indicate prompt recovery and minimal degradation. High grades mean the original mineralogy has been partially replaced by terrestrial alteration products. Weathering grade affects both scientific value and long-term stability in a collection.

What a Bulletin Entry Cannot Tell You

The Bulletin certifies that a meteorite of a specific name and type exists and has been analyzed. It does not certify any individual specimen you might purchase.

A critical distinction

A seller can accurately reference a real Bulletin entry while selling you a terrestrial rock. The Bulletin citation is a necessary but not sufficient verification. You also need a certificate of authenticity from a reputable dealer that specifically identifies your specimen by weight and links it to the classification record.

The combination of a verifiable Bulletin citation and a specimen-specific certificate of authenticity from an IMCA member dealer is the standard of documentation for a properly provenanced meteorite.

Learn more about how to verify a meteorite is real.

How to Look Up Any Meteorite

Go to lpi.usra.edu/meteor/metbull.php and use the search box to enter the meteorite name exactly as listed.

For NWA meteorites, search the full name including the number: Northwest Africa 17472 or NWA 17472

For named locality meteorites, search the locality name followed by the number: Guemar 002 or Adrar 013

The entry will return the full classification record including all fields described in this guide.

Every product listing at Treasure Coast Meteorite Co. includes a direct link to the relevant Bulletin entry for classified specimens. Unclassified material is clearly stated as such in the listing title and description and will not have a MetBull reference. You should verify the entry before purchasing from us, and you should verify it on any other site before purchasing from them as well. A seller who provides that link and encourages you to check it independently is a seller worth trusting.

Related Guides

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Lunar Meteorites Martian Meteorites All Meteorites

Frequently Asked Questions

Is every meteorite in the Meteoritical Bulletin authentic?

Yes. Bulletin approval requires laboratory analysis and peer review by the Meteoritical Society's Nomenclature Committee. A meteorite listed in the Bulletin has been scientifically confirmed as a meteorite of a specific type. What the Bulletin cannot confirm is whether any individual specimen offered for sale is actually from that classified lot, which is why a certificate of authenticity from a reputable dealer is also required.

What does "approved" mean in a Bulletin entry?

Approved means the classification has been reviewed and accepted by the Meteoritical Society's Nomenclature Committee. Provisional entries exist in the database before full approval. Always look for approved status when verifying a specimen's credentials.

Can I trust an NWA meteorite without a specific find location?

Yes, with caveats. NWA meteorites are recovered from known meteorite-rich regions in Northwest Africa, but precise find coordinates are often undocumented because the stones pass through multiple dealers before reaching a classifier. The classification itself confirms the specimen is a meteorite of the listed type regardless of imprecise provenance. For specimens where exact provenance matters scientifically, named locality meteorites with documented coordinates are preferable.

What is the difference between MB 113 and MB 114?

MB numbers refer to sequential issues of the Meteoritical Bulletin publication. Each issue approves a batch of newly classified specimens. The MB number in an entry tells you which issue published the classification and can be used to look up the full issue in the scientific literature if needed.

Does Treasure Coast Meteorite Co. provide Meteoritical Bulletin links with every listing?

Yes. Unless specifically stated as unclassified in the listing title or description, every specimen sold by Treasure Coast Meteorite Co. is Meteoritical Bulletin classified, and every classified listing includes a direct link to the official database entry. Every purchase ships with a certificate of authenticity from Treasure Coast Meteorite Co., IMCA #3323.

About the Author

Brian McDonald is a veteran and the owner of Treasure Coast Meteorite Co., based on Florida's Treasure Coast. An IMCA member (#3323), he specializes in authentic meteorites with verified documentation, including classified specimens with Meteoritical Bulletin entries and ethically sourced unclassified material. His mission is simple: put real pieces of the solar system in the hands of people who will appreciate them. Read his full story →