Meteorite Classification

Meteorite classification helps organize meteorites according to their composition, mineralogy, formation history, and parent-body processes. While older schemes divided meteorites into stony, stony-iron, and iron meteorites, modern meteoritics uses a more refined framework that distinguishes primitive and differentiated materials, as well as numerous groups, clans, and subgroups.

How Meteorites Are Classified

Meteorite classification has evolved considerably since the beginnings of meteoritics in the late eighteenth century. Traditional systems divided meteorites into three broad compositional classes: stony meteorites, stony-iron meteorites, and iron meteorites. This approach remains useful as a practical introduction, but modern classification goes much further.

Today, meteorites are classified not only by what they contain, but also by how they formed, what thermal or aqueous processes affected them, and from which parent body they originated. Mineralogy, chemistry, texture, and isotopic composition all play a role in modern meteorite classification.

Primitive and Differentiated Meteorites

From a scientific point of view, meteorites can be broadly divided into two major categories: primitive meteorites and differentiated meteorites.

Primitive Meteorites

Primitive meteorites preserve material that formed very early in Solar System history and remained relatively undifferentiated. Most belong to the chondrites, the most abundant meteorite class. Chondrites often contain chondrules, fine-grained matrix, metal, and sulfides, and they provide essential information about the earliest stages of Solar System formation.

Primitive meteorites include the major chondrite clans and groups, such as ordinary chondrites, carbonaceous chondrites, and enstatite chondrites, as well as certain transitional types known as primitive achondrites.

Differentiated Meteorites

Differentiated meteorites come from parent bodies that experienced internal heating, melting, recrystallization, and chemical segregation. In such bodies, denser metallic phases tended to form cores, while silicates formed mantles and crusts.

This category includes many achondrites, as well as iron meteorites and stony-iron meteorites. Some differentiated meteorites originate from major parent bodies such as the Moon, Mars, or asteroid Vesta, while others come from parent bodies that remain less certain.

The Traditional Three Main Classes

Stony Meteorites

Stony meteorites are composed predominantly of silicate minerals. They include both chondrites and achondrites. Chondrites are primitive, while achondrites are generally igneous or brecciated rocks that formed on differentiated parent bodies.

Stony-Iron Meteorites

Stony-iron meteorites contain substantial amounts of both silicate minerals and metallic iron-nickel. The most famous examples are pallasites, with olivine crystals enclosed in metal, and mesosiderites, which are brecciated mixtures of silicates and metal.

Iron Meteorites

Iron meteorites are dominated by metallic iron-nickel. They are generally interpreted as samples of metallic cores or related regions of differentiated asteroids. Their internal structures, especially when etched, provide important information about cooling history and parent-body evolution.

Primitive Meteorite Groups

The principal primitive meteorites include:

• Ordinary chondrites (H, L, LL)
• Carbonaceous chondrites (such as CI, CM, CO, CV, CR, CK, CH, CB)
• Enstatite chondrites (EH, EL)
• Rumuruti chondrites
• Kakangari-related meteorites
• Primitive achondrites such as acapulcoites, lodranites, winonaites, brachinites, and related groups

Differentiated Meteorite Groups

The principal differentiated meteorites include:

• Achondrites, including HED meteorites, aubrites, angrites, ureilites, lunar meteorites, and Martian meteorites
• Stony-iron meteorites, including pallasites and mesosiderites
• Iron meteorites, divided into several chemical groups and ungrouped irons

Why Meteorite Classification Matters

Meteorite classification is essential because it connects each specimen to a broader scientific context. It helps determine how a meteorite formed, what type of parent body it came from, and what kind of information it preserves about the early Solar System.

For collectors, dealers, museums, and researchers, classification also provides the framework for proper identification, comparison, and documentation. A meteorite is not simply a stone from space: it is a sample from a specific geological and cosmochemical context.

This Classification Index

This page serves as a practical introduction to the principal meteorite classes, clans, groups, and subgroups. The classification table and linked pages are intended to help visitors navigate the diversity of meteorites, from primitive chondrites to differentiated planetary materials.

Official meteorite names and accepted classifications are maintained through the Meteoritical Bulletin Database, and this index is intended to remain aligned with that evolving scientific framework.

Frequently Asked Questions About Meteorite Classification

What are the main classes of meteorites?

The traditional main classes are stony meteorites, stony-iron meteorites, and iron meteorites. Modern classification also distinguishes primitive and differentiated meteorites.

What is the difference between primitive and differentiated meteorites?

Primitive meteorites preserve relatively early Solar System material with limited melting, while differentiated meteorites come from parent bodies that underwent internal heating, melting, and chemical segregation.

What are chondrites?

Chondrites are primitive stony meteorites that often contain chondrules and preserve material formed very early in Solar System history.

What are achondrites?

Achondrites are meteorites that do not contain chondrules and generally formed through igneous or impact-related processes on differentiated parent bodies.

What are stony-iron meteorites?

Stony-iron meteorites contain substantial amounts of both silicate minerals and metallic iron-nickel. Pallasites and mesosiderites are the main examples.

What are iron meteorites?

Iron meteorites are dominated by iron-nickel metal and are generally interpreted as samples of metallic cores or related regions of differentiated asteroids.

Why is meteorite classification important?

Classification helps determine a meteorite’s origin, formation history, scientific significance, and relationship to other meteorites and parent bodies.

Who maintains official meteorite classifications?

Official meteorite names and classifications are maintained through the Meteoritical Bulletin Database and the Meteoritical Society’s nomenclature system.

Meteorite Classification Index

> Classification of meteorites