From the Meteoritical Bulletin #90:
- Northwest Africa 2200
- Purchased August, 2004
- Lunar meteorite (feldspathic breccia)
A completely crusted 552 g ellipsoidal stone found in the Atlas
Mountains, Morocco was purchased in Erfoud by a Moroccan dealer for D. Gregory (Gregory)
in 2004 August. Classification and mineralogy (S. Kuehner and A. Irving, UWS):
Breccia consisting of coarse, greyish to whitish lithic and mineral clasts in a darker
glassy to finely crystalline matrix. Lithic clasts are mainly very fine grained,
quench-textured, feldspathic rocks that probably result from impact melting of
anorthositic to gabboic anorthositic precursors. A small percentage of the clasts are
ophitic-textured mare basalts. Mineral clasts include anorthitic plagioclase,
olivine (Fa30-60), exsolved pigeonite, irregular grains of metal (with ~10-45
wt.% Ni), Ti-rich chromite, Ti-poor chromite, pyroxene-like glass(?) schreibersite (~5
wt.% Ni), clinopyroxene, ilmenite, troilite and rare zirconolite. Clinopyroxene and
orthopyroxene grains in mineral and lithic clasts have Fe/(Fe+Mg) = 0.258 to 0.482, and 19
of 23 analyses have Ti/(Ti+Cr) = 0.53-0.75. FeO/MnO ratios measured for olivine
(99.7, 105.5), clinopyroxene (73.7) and orthopyroxene (65.4) are unmistakably within the
ranges for these minerals in known lunar rocks. Feldspar grains in mineral and
lithic clasts have a narrow compositional range of An95.8-97.4. The
combination of anorthitic plagioclase and ferroan mafic silicates suggests that the
majority of the material in this specimen was derived from FAN-suite lithologies (Kuehner
et al., 2005). Specimens: type specimens, 20.5 g, one polished thin section, and one
polished mount, UWS; main mass, Gregory. |
