EUCRITE

 

The “HED meteorites” (howardites & eucrites & diogenites) are unusual rock samples from the asteroid belt (between Mars & Jupiter) in that they have been successfully linked to a known, named parent body.  Most meteorites are simply referred to as coming from “some parent body” in the asteroid belt.  HED meteorites are known to have come from the asteroid Vesta.  The most common Vestan rocks are eucrites (see sample below).  Eucrites are basalt rocks from Vesta's crust.  They range in specific lithology from non-cumulate basalt to cumulate basalt to brecciated basalt to regolith breccias dominated by basalt clasts.

 

The sample shown below is from the NWA 3359 Meteorite.  It was found in northwestern Africa in 2005.  It’s lithology is usually referred to as a polymict eucrite, which is a Vesta regolith breccia dominated by large, irregularly-shaped, dark-colored clasts of basalt.  Mineralogically, Vestan basalt is principally composed of pigeonite pyroxene and calcic plagioclase feldspar (anorthite).

 

This particular rock has not been dated, but published dates from other eucrites show that the primary crystallization age of Vestan basalt is 4.565 billion years.

 

Eucrite (polymict eucrite slice, 3.6 cm across at its widest).  This is a breccia dominated by large, irregularly-shaped, dark gray-colored clasts of eucrite (Vestan basalt).

Eucrite (polymict eucrite slice).  Flip side of specimen shown above.

 


 

(More info. on the NWA 3359 Meteorite)

 


 

 

Home page