Ron wrote: > It was not uncommon to see a discontinuity where apparently crystallization > proceeded from different regions with the Widmanst�tten patterns oriented > differently, and approached an interface between them. It's not so much a > wedge, but rather a zone between the two areas where there is no pattern, > and this zone can be several cm. wide.
BUCHWALD V.F. (1975) Handbook of Iron Meteorites, Vol. 2, pp. 584-593: Each austenite grain has, in the usual way, formed a fine Widmanst�tten pattern, but it is interesting to note that near the boundary the pattern becomes very indistinct, apparently because only one of the four possible Widmanst�tten planes has been able to develop. COHEN E. (1905) Meteoritenkunde, Heft III, pp. 324-342: COHEN E. (1905) Meteorites, Volume III, pp. 324-342: Ueber ein Meteoreisen von Mukerop, Bezirk Gibeon, Grossnamaland On a meteoric iron from Mukerop, Gibeon region, Grossnamaland Von A. Brezina und E. Cohen (By A. Brezina and E. Cohen). Mit Tafel VI. (With Table VI). The etched surface is composed of three parts which are clearly discernible. One part comprising about 1/3 of the etched surface assumes a matte color and a weak, greasy sheen when etched; at a cursory glance, this sheen looks homogenous and resembles the dense, nickel-rich ataxites. But when studied carefully, especially with a light source infalling at a shallow angle and using a loupe, you recognize a structure of fine octahedritic lamellae*. The reason why this structure is so indistinctly visible is, on the one hand, due to the extremely fine taenite lamellae, and, on the other, it is due to the bands and fields consisting of the same fine-grained kamacite that is weakly shimmering under the microscope. * Footnote by the authors: Interestingly, the more you etch the less discernible the Widmanst�tten pattern becomes. ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
