A Metallographic Study of the Angra Dos Reis (Iron) Meteorite

H. J. Axon and C. V. Waine
Metallurgy Department, The University, Manchester, M13 9PL

Summary: The Angra dos Reis (iron) has been studied metallographically and an attempt has been made to discuss the circumstances under which the following elements of structure formed: clear etching and frosty etching kamacite, decorated Neumann lines, giant rhabdites, plate rbabdites, rhabdite clusters, microrhabdites, cohenite, and remelted troilite. The remelted troilite is taken to indicate a shock event. However, since there are no metallographically visible indications of shock in the kamacite and since the back reflection X-ray diffraction pattern shows only very faint Debye-Scherrer arcs superimposed on a pattern of sharp spots, it is concluded that the shock event took place at a temperature that allowed shock effects to anneal out of the kamacite almost completely. A submicroscopic precipitate in the metallic matrix is observable with the electron microscope and may represent the final precipitation of phosphide from shocked kamacite.

Mineralogical Magazine; March 1971 v. 38; no. 293; p. 94-101; DOI: 10.1180/minmag.1971.038.293.13
© 1971, The Mineralogical Society
Mineralogical Society (www.minersoc.org)