For readers who want the full picture
Detailed explanation
Eucrites are mainly basaltic crustal rocks, while diogenites are more orthopyroxene-rich rocks from deeper levels. Howardites are breccias mixing material from both groups.
Spectral and geochemical matches support Vesta as their common parent body.
- Groups
- howardite · eucrite · diogenite
A differentiated asteroid
The diversity of HED rocks records crust, deeper igneous levels and later impact mixing on an early differentiated body.
Howardites, eucrites and diogenites
Eucrites are mainly basaltic crustal rocks composed chiefly of pyroxene and plagioclase. Diogenites are coarser, orthopyroxene-rich rocks formed at depth. They represent different levels of a differentiated parent body.
Howardites are polymict regolith breccias: impacts mixed fragments of eucrites, diogenites and other surface material. The three names are not a quality scale but different rock types and mixtures.
Why Vesta is considered the parent body
The reflectance spectra of HED minerals closely match large parts of asteroid 4 Vesta. Oxygen isotopes and mineral chemistry also show that howardites, eucrites and diogenites are genetically related.
The Dawn spacecraft mapped a basaltic world reshaped by giant impacts. Fragments may travel from Vesta into the Vestoid family and through resonances to near-Earth orbits. The link is strong even though each individual ejection event is unknown.
Short & simple
The essentials in 30 seconds
- Howardites, eucrites and diogenites form a major achondrite family, generally linked to Vesta.
- Eucrites are mainly basaltic crustal rocks, while diogenites are more orthopyroxene-rich rocks from deeper levels. Howardites are breccias mixing material from both groups.
- Spectral and geochemical matches support Vesta as their common parent body.
Sources & editorial note
Sources & databases
Editorially paraphrased prefill, reviewed 12 August 2026. The linked sources support further specialist verification.