AGOULT

An 82 g stone with fresh fusion crust was found in Morocco. Many paired stones were subsequently recovered, bringing the total known weight to over 650 g. This eucrite has an unbrecciated, homogeneous, very fine-grained, granulitic texture composed of pyroxene (~100 µm) and plagioclase (~50 × 300 µm). Opaques present include ilmenite, Ti-chromite, and FeS. Agoult was probably formed in the deep crust.

In their studies of a small number of metamorphosed eucrites, Yamaguchi et al. (2009) determined that a few of them exhibited differences from Main Group–Nuevo Laredo trend eucrites in that they show varying degrees of LREE depletion with positive Eu anomalies. They believe these features are the result of rapid partial melting caused by magma plume intrusions and/or impact events, with subsequent melt extraction. These reheating events were superimposed over a protracted metamorphism already occurring within the deep crust. The team proposes to call these eucrites (e.g., Agoult, A-87272, DaG 945, and NWA 2362) "residual eucrites", which lost a partial melt that contaminated the Main Group–Nuevo Laredo trend eucrites to produce the Stannern trend eucrites.

It may be noteworthy that Agoult has been described by some investigators as having elemental, chemical, and textural characteristics similar to those of Ibitira. Ibitira has since been designated as an ungrouped eucrite-like achondrite based on certain anomalous elemental ratios and an anomalous O-isotopic composition (Mittlefehldt, 2005). The specimen of Agoult pictured above is a 0.25 g partial slice.

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