DAR AL GANI 055

A stone weighing 451 g was found in the Libyan Sahara. It is shocked to stage S2 and has a weathering grade of W1. The main mass is at the University of Humboldt, Berlin. A 703 g stone recovered nearby, DaG 056, is thought to be paired with DaG 055 based on similar cosmic-ray exposure ages (6.1 and 6.3 m.y. respectively), similar bulk compositions, and their close proximity when found. In 1998, stones were found nearby that may also be paired with DaG 055—DaG 429 (253 g) and DaG 430 (572 g; CRE age of 5.9 m.y.). Interestingly, only DaG 056 has been found to contain solar-type rare gases indicative of a regolith origin. Another type-3 carbonaceous chondrite, NWA 1665, has an O-isotope composition that plots near the DaG 055 pairing group, and it has been suggested that it may also be related.

The O-isotope values of DaG 055 plot in the middle of the CK field (Clayton and Mayeda, 1999). Refractory lithophile element abundances fall within the CV–CK range, while siderophile and chalcophile abundances are more CV-like (Huber et al., 2006). It has equilibrated matrix olivines with a composition of Fa30.5 (±0.5), in the range of the CK group (Fa31 (±3). DaG 055 also shows similarities to the CK3 Camel Donga 003, but exhibits lower 129Xe/132Xe ratios than is normal for the CK group.

It has recently been demonstrated by Greenwood et al. (2009) that the CK group is consistent with a metamorphic extension of the CV group (see the Dhofar 015 page for more detailed information). The specimen of DaG 055 shown above is a 0.8 g fragment partially covered by fusion crust.

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