For readers who want the full picture
Detailed explanation
Achondrites have igneous or strongly reworked textures. They come from bodies where original material was at least partly melted and separated.
They include asteroidal groups such as HED, aubrites, angrites and ureilites, as well as lunar and Martian meteorites.
- Defining feature
- no chondrules
Resemblance to terrestrial rocks
Because both can form through geological melting and crystallisation, many achondrites resemble terrestrial basalts or plutonic rocks. Secure identification requires laboratory data.
Differentiation: from starting material to planetary rock
When a small planetary body is heated strongly enough, part of it melts. Dense metal may sink inward while silicate melts form mantle and crust. Achondrites are products or remnants of such processes.
Their textures may be basaltic, plutonic, brecciated or strongly recrystallised. The absence of chondrules is important but does not by itself identify a group.
Asteroidal and planetary achondrites
HED meteorites, angrites, aubrites and ureilites represent different asteroidal parent bodies. Lunar and Martian meteorites are planetary achondrites whose origins are supported by several independent laboratory indicators.
Primitive achondrites record only partial melting and preserve more original features. The boundary between primitive and fully differentiated describes a process, not a simple visual category.
Short & simple
The essentials in 30 seconds
- Stony meteorites without chondrules, shaped by melting and recrystallisation.
- Achondrites have igneous or strongly reworked textures. They come from bodies where original material was at least partly melted and separated.
- They include asteroidal groups such as HED, aubrites, angrites and ureilites, as well as lunar and Martian meteorites.
Sources & editorial note
Sources & databases
Editorially paraphrased prefill, reviewed 12 August 2026. The linked sources support further specialist verification.