Diogenite
Polymict
Purchased October 2002
no coordinates recorded
A single, fusion-crusted stone weighing 803 g was purchased in Morocco by A. and G. Hupé. The meteorite was designated NWA 1648 and classified at the University of Washington as a rare polymict diogenite. This brecciated diogenite comprises a variety of mineral and lithic clasts, primarily low-Ca orthopyroxene, but also including a small number of cumulate and basaltic eucrite clasts and quenched glass, along with minor amounts of anorthite, silica, ilmenite, troilite, and breakdown products of former pyroxferroite.
Northwest Africa 1648 contains a large component of orthopyroxene clasts (>80 vol%) that exhibits a wide compositional variation as reflected by a wide range of Fe/Mg ratios (= Fa ÷ [100 – Fa]); the Fa value is 28.2–34.8. This range is consistent with the theory that diogenites are orthopyroxene cumulates resulting from fractional crystallization in a number of compositionally distinct basaltic magma sources.
Additional details about the polymict diogenite group can be found on the NWA 1239 page. An alternative classification system for the diogenites based on mineralogical and petrographical features has been proposed by Beck and McSween (2010), and modified by Wittke et al. (2011). The photo of NWA 1648 shown above is a 1.02 g partial slice. The photo below allows a high-resolution view of a large slice of NWA 1648 in the R. A. Langheinrich Collection.
