The Hvittis enstatite chondrite breccia contains 5¿2 vol% dark clasts which appear to be impact melt-rocks. The largest clast (Clast A) is 2.5 cm in diameter; it has an igneous texture, no chondrules, and is depleted in metallic Fe, Ni and sulfide. Its fine grain size, low-Ni kamacite and schreibersite, and rare martensite resulted from rapid cooling. The abundance of melt-rock clasts in Hvittis suggests that the breccia resided at its parent body surface. However, the apparent absence of EL chondrites with solar wind-implanted rare gases suggests that the EL parent body was too small to develop a substantial regolith. The bulk composition of Clast A is very similar to that of average ambrites, except for a sevenfold enrichment in S, Cr, and Mn. These elements are concentrated in the sulfides. It thus is possible that the clast was derived from one of the sulfide-rich regions of the Hvittis matrix. If so, then aubrites may be genetically related to EL chondrites. |