NORTHWEST AFRICA 725

Eleven pieces of this Moroccan primitive winonaite, weighing a total of 3,824 g (total weight of the entire pairing group is ~5.1 kg), were recovered by a French team under the organization of Bruno Fectay and Carine Bidaut. Although the coordinates of the recovery location in Tissemoumine, Morocco were recorded by GPS equipment, the more general "NWA" name was accepted as the official name by the Meteoritical Society. This meteorite is of great interest due to its abundance of relict chondrules.

*Previously, a division of the acapulcoite–lodranite meteorites based on metamorphic stage was proposed by Floss (2000) and Patzer et al. (2003). A similar distinction can be made among the winonaites in our collections, although there is not yet an analog of the IAB complex irons for the acapulcoite–lodranite PB. NWA 725 and its pairing group contains intact chondrules and is among the most primitive of winonaites. However, it still experienced extensive heating and possibly a low degree of silicate partial melting, resulting in a depletion of certain trace elements. Progressive degrees of thermal metamorphism leads to samples exhibiting the early stages of melting and loss of low-melting phases, and having highly recrystallized textures, characteristics analogous to the "typical" acapulcoites. Progressing along the metamorphic contiuum leads to a loss of some plagioclase and sulfide phases, called the "transitional" stage in the acapulcoite–lodranite metamorphic sequence. Finally, at the highest temperatures, crystallization from residual melt material results in a depletion of the low-melting point components including plagioclase, troilite, and metal. Samples representing this advanced metamorphic stage are known as lodranites in the acapulcoite–lodranite metamorphic sequence—the term "evolved" could be used for such a metamorphic stage in the winonaite group.

**Although initially classified as an acapulcoite, a recent O-isotopic analysis of a portion of the main mass (in the collection of S. Turecki) by the Open University, UK, resolves the material clearly within the winonaite field: "In particular, the Δ17O value of -0.431 is in reasonable agreement with the mean value of -0.48 for the winonaite–IAB complex group determined by Clayton and Mayeda (1996)." In addition, when plotted on a diagram comparing the Δ17O-isotopic value vs. Fa mol% in olivine (Rumble, III et al, 2005), NWA 725 (Fa 6.1; Δ17O-isotopic value taken from the main mass [Turecki, 2005; pers. comm.]) and the winonaites NWA 1463 (Fa 7.4; Δ17O = -0.45‰), NWA 1457 (Fa 5; Δ17O = -0.40 ±0.03‰), and NWA 1058 (Fa 6.5; Δ17O = -0.53‰) all plot very close together within the winonaite field. The inference can thus be made that NWA 725 is actually a winonaite, likely paired with the primitive winonaites NWA 1463 and 1058 (NWA 1052 and NWA 1054 are also likely members of this pairing group).

The presence of relict chondrules in NWA 725 is a feature which suggests that the winonaites are actually metachondrites, based on terminology associated with several newly recognized groups of chondrule-free, texturally evolved chondrites with elemental ratios and O-isotopic compositions showing affinities to existing chondrite groups (Irving et al., 2005). Further information about the classification of this meteorite and its probable pairings can be found on the NWA 1058 page. The NWA 725 specimen pictured above is a 1.3 g partial slice showing many clear, intact chondrules.

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