The last issue of Geochimica et Cosmochimica (Vol. 62, No. 4. pp. 715-724) contains an article by John Wasson, et al., that opines that the Albion IVA iron is probably a piece of Gibeon!Hello Steve, hello List!
A single 12.28 kg mass was found on a wheat farm by K. Oliphant. Description and classification (C.F. Lewis, ASU; J.T. Wasson, UCLA): bulk composition, 8.20 wt% Ni, 2.04 ppm Ga; bandwidth ~0.3 mm; very similar to Gibeon in composition and appearance but contains vugs with botryoidal linings (see Marvin et al., 1996). Specimens: type specimen, ASU; main mass, unknown (Met.Bull. 81, 1997, A159).
OLSEN E.J. (1981) Vugs in ordinary chondrites (Meteoritics 16, 45-59).
U.B. Marvin et al. (1996) Drusy vugs in the Albion iron meteorite: Mineralogy and textures (abs. Meteoritics 31, 1996, A083):
Albion (name submitted to the Nomenclature Committee of the Meteoritical Society), a IVA fine octahedrite, is unique in having vugs scattered throughout the otherwise orderly Widmanstätten structure. The most prominent vugs are open cavities, up to about 5 x 9 mm, partially filled with drusy spheroidal masses. The final growth phase in Vug A was the deposition of a thin rim chiefly of kamacite on all exposed surfaces. Such vugs are surrounded by thin zones, <= 2 mm wide, of granulated kamacite. A second type of vug lining, observed by Buchwald, consists of masses of cubic Fe crystals with <= 0.5 wt% Ni. Still other vugs occur as narrow voids, <= 2 mm long, and as minute vacuoles a few micrometers across, along the kamacite-taenite grain boundaries of the Widmanstätten patterns. The spheroidal masses consist mainly of irregular kamacite grains, 1-35 mm across, containing 2-3.5 wt% Ni, plus a few rounded segregations of Ni-rich tetrataenite with 55.6 wt% Ni. Enmeshed in both metals are thin, branching films of troilite that appears to have invaded and corroded them. Scattered throughout the spheroids are blocky, euhedral grains of daubreelite (FeCr2S4) and scarcer ones of euhedral schreibersite [(Ni0.54Fe0.46)3P]. The Ni content of kamacites rises steadily from 2-3.5 wt% in the spheroids to about 5.3 wt% in the granulated metal zone to 7.1 wt% Ni in the Widmanstätten patterns. Along the same traverses, the content of Ni in the tetrataenite grains drops precipitously from about 55 wt% Ni in the spheroids and granulated zone to an average of 33.7 wt% Ni in the taenite of the main mass. We have observed no evidence of shock metamorphism in the meteorite. Clearly, the Albion iron has been subject to the passage of reactive fluid phases during one or more episodes of its history.
M.E. Petaev et al. (1996) Drusy vugs in the Albion iron meteorite: Early speculations on the origin (abs. Meteoritics 31, 1996, A107).
Best wishes from rainy, stormy and cold Southern Germany
Bernd