Luna 16: An opaque mineral study and a systematic examination of compositional variations of spinels from Mare Fecunditatis Article

Haggerty, SE. (1972). Luna 16: An opaque mineral study and a systematic examination of compositional variations of spinels from Mare Fecunditatis . EARTH AND PLANETARY SCIENCE LETTERS, 13(2), 328-352. 10.1016/0012-821X(72)90109-4

cited authors

  • Haggerty, SE

authors

abstract

  • Opaque minerals identified by reflection microscopy and electron microprobe include ilmenite, members of the chromite-pichrochromite-hercynite-ulvospinel series, rutile, troilite, metallic iron and metallic nickel-iron alloys. Spinel compositions indicate an extensive but incomplete solid solution series between FeCr2O4-FeAl2O4 and Fe2TiO4. Members of this series are common to samples from each of the Apollo landing sites but the Luna 16 spinels are characterized by High Al (15-25% Al2O3), high Mg (4-9% MgO) contents, by compositions intermediate between (FeCr2O4-FeAl2O4)-Fe2TiO4 typical of Apollo 11, and by considerable variation of Cr/Al as a function of Fe/Mg not previously observed. The ratios Cr/Al and Fe/Mg show maximum variability in low-Ti chromites whereas intermediate titanian-chromites and chromian-ulvospinels show less variation of Cr/Al, and Fe/Mg is constant and high ({reversed tilde equals}0.97). Ilmenite contains between 0.1 and 5.7 wt.% MgO; high geikielite contents and contrasting coexisting ilmenite textures (skeletal and phenocrystic) suggest possible reaction of early formed armalcolite with liquid. Shock deformation of ilmenite gives rise to simple lamellar twins in low intensity shocked fragments; complexly deformed twins and evidence of shock-induced melting are present in highly shocked fragments; and peripheral annealing of preexisting twin lamellae, associated with partial melting, is recorded for the first time in lunar ilmenite. © 1972.

publication date

  • January 1, 1972

published in

Digital Object Identifier (DOI)

start page

  • 328

end page

  • 352

volume

  • 13

issue

  • 2