For readers who want the full picture
Detailed explanation
Mesosiderites contain broadly comparable proportions of iron-nickel metal and silicate debris. Their silicates often resemble basaltic and deeper rocks from differentiated asteroids.
Their brecciated texture indicates violent collision, mixing and later thermal evolution.
- Texture
- metal-rich breccia
Not pallasites
Where pallasites usually show individual olivine crystals in metal, mesosiderites consist of complexly mixed rock fragments and metal. The distinction is petrographic, not merely visual.
An impact breccia mixing two asteroid reservoirs
Mesosiderites mix basaltic and deeper-formed silicate rocks with iron-nickel metal. Large collisions had to bring together material from crust and a metal-rich interior.
Many samples then cooled slowly and were thermally modified after mixing. Their origin is therefore a multi-stage history rather than one simple impact.
Texture and subgroups
Metal and rock fragments may be mixed on fine to coarse scales. The silicate component commonly contains pyroxene and plagioclase and has affinities with basaltic achondrites, but mesosiderites are not simply HED meteorites with metal added.
Petrologic and chemical subgroups organise different silicate types and metamorphic grades. Precise assignment requires petrography and laboratory analysis.
Short & simple
The essentials in 30 seconds
- Brecciated stony-iron meteorites made from mixed crustal material and metal.
- Mesosiderites contain broadly comparable proportions of iron-nickel metal and silicate debris. Their silicates often resemble basaltic and deeper rocks from differentiated asteroids.
- Their brecciated texture indicates violent collision, mixing and later thermal evolution.
Sources & editorial note
Sources & databases
Editorially paraphrased prefill, reviewed 12 August 2026. The linked sources support further specialist verification.