Eucrite
| Eucrite | |
|---|---|
| — Group — | |
Stannern eucrite, found in the Czech Republic. | |
| Compositional type | Stony |
| Type | Achondrite |
| Class | Asteroidal achondrite |
| Clan | HED meteorite |
| Subgroups |
|
| Parent body | 4 Vesta and others |
| Composition | Basaltic rock, mostly Calcium-poor pyroxene, pigeonite, and Calcium-rich plagioclase (anorthite) |
| Total known specimens | >100 |
GRA98033 a brecciated eucrite about 5 cm across, found in the Graves Nunataks region of Antarctica. | |
Eucrites are achondritic stony meteorites, many of which originate from the surface of the asteroid 4 Vesta and are part of the HED meteorite clan. They are the most common achondrite group with over 100 meteorites found.
Eucrites consist of basaltic rock from the crust of 4 Vesta or a similar parent body. They are mostly composed of calcium-poor pyroxene, pigeonite, and calcium-rich plagioclase (anorthite).
Based on differences of chemical composition and features of the component crystals, they are subdivided into several groups:
- Non-cumulate eucrites are the most common variety and can be subdivided further:
- Main series eucrites formed near the surface and are mostly regolith breccias lithified under the pressure of overlying newer deposits.
- Stannern trend eucrites are a rare variety.
- Nuevo Laredo trend eucrites are thought to come from deeper layers of 4 Vesta's crust, and are a transition group towards the cumulate eucrites.
- Cumulate eucrites are rare types with oriented crystals, thought to have solidified in magma chambers deep within 4 Vesta's crust.
- Polymict eucrites are regolith breccias consisting of mostly eucrite fragments and less than one part in ten of diogenite. They are less common.