Howardite
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Howardites are achondritic stony meteorites that originate from the surface of the asteroid 4 Vesta, and as such are part of the HED meteorite group. There are about 50 distinct members known.
They are a regolith breccia consisting mostly of eucrite and diogenite fragments, although carbonaceous chondrules and impact melt can also occur. The rock formed from impact ejecta which was later buried by newer impacts and lithified due to the pressure from overlying layers. Regolith breccias are not found on Earth due to a lack of regolith on bodies which have an atmosphere.
Howardites are named for Edward Howard, a pioneer of meteoritics. An arbitrary divide between howardites and the polymict eucrites is a 9:1 ratio of eucrite to diogenite fragments.
[edit] External links
- HED Group - Meteorites from Vesta
- NWA 1281 (Howardite) from Meteorites Australia - Meteorites.com.au
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