Lunar Meteorite Update
THE METEORITICAL BULLETIN
E-mail Announcement 84-1, June 2, 2000
Jeffrey N. Grossman, Editor (jgrossman@usgs.gov)
Dhofar 025 Lunar anorthositic regolith breccia found in Oman.
Dhofar 026 Lunar anorthositic crystalline melt breccia found in Oman.
Northwest Africa 032 Lunar olivine-pyroxene basalt from Morocco.
The entire text of the new Meteoritical Bulletin (abstract below) may be viewed at
http://www.uark.edu/campus-resources/metsoc/metbull/mb84v2.pdf
Information in this document is subject to minor revision until
July 13, 2000.
Dhofar 025 18=BA24.2’N 54=BA09.1’E
Oman
Found 2000 March 5
Lunar meteorite (anorthositic regolith breccia)
A brownish gray stone weighing 751 g was found in the Dhofar region of Oman. Mineralogy and classification (M. Nazarov and M. Ivanova, Vernad): fusion crust absent; meteorite is a regolith breccia
containing numerous mineral fragments and clasts of feldspathic
rocks embedded in a glass-rich matrix; schlieren and vesicles are abundant; feldspar, An95-96; pyroxene, En74-84Wo3-6 (Fe/Mn =3D 50-70 at.); olivine, Fo70-78 (Fe/Mn =3D 91-97 at.); accessory minerals are silica, Ti-rich alumochromite, troilite, and FeNi metal; meteorite has a prominent positive Eu anomaly (Sm/Eu =3D 1.95); terrestrial weathering is not significant. Specimens: type specimen, 102 g plus two thin sections, Vernad; main mass with anonymous finder.
Dhofar 026 18=BA13.6’N 54=BA06.7’E
Oman
Found 2000 March 6
Lunar meteorite (anorthositic crystalline melt breccia)
A brownish gray stone weighing 148 g was found in the Dhofar region of Oman. Mineralogy and classification Mineralogy and classification (M. Nazarov and M. Ivanova, Vernad): fusion crust absent; meteorite is a clast-poor, anorthositic, crystalline melt breccia containing rare mineral fragments and clasts of feldspathic rocks embedded in a completely devitrified fine-grained matrix; vesicles are abundant; sphere-shaped, chondrule-like inclusions and rare impact melt veins are present; feldspar, An96-98; olivine (a dominant mafic phase), Fo61-79 (Fe/Mn =3D 80-120 at.); low-Ca pyroxene, En53-63Wo8-20 (with 0.13-0.84 wt% TiO2, Fe/Mn =3D 40-60 at.); high-Ca pyroxene, En43-50 Wo27-33 (with 1.1-3.5 wt% TiO2, Fe/Mn =3D 40-50 at.); accessories minerals are silica, ilmenite (MgO =3D 7 wt%), troilite, and FeNi metal; a prominent positive Eu anomaly (Sm/Eu =3D 1.04) is present; terrestrial weathering is not significant. The meteorite is completely different in texture and composition from Dhofar 025, but pairing must still be considered due to the proximity of the finds to one another. Specimens: type specimen, 41 g plus two thin sections, Vernad; main mass with anonymous finder.
Northwest Africa 032 near 30=BA22’N 5=BA3’W
Morocco, near Algerian border
Found 1999 October
Lunar meteorite (olivine-pyroxene basalt)
A stone of ~300 g was found in the desert (see Table 9). Classification and mineralogy (T. Fagan, UHaw; T. Bunch and J. Wittke, NAU): olivine, pyroxene, and chromite phenocrysts occur in a groundmass of elongate, zoned pyroxene (En1-25Wo15-25) and feldspar (~An85) crystals radiating from common nucleation sites; opaque phases include elongate, skeletal ilmenite, troilite, and trace metal; olivine phenocrysts (~12 vol%) up to 300 mm are zoned from Fo65 (cores) to Fo60 (rims), and commonly have chromite inclusions; pyroxene phenocrysts (~5 vol%) are complexly zoned, with En40-50Wo20-40 and En15-25Wo10-20 domains; both olivine and pyroxene phenocrysts surrounded by Fe-rich quenched margins (olivines, ~Fo30; pyroxenes, En5-25Wo15-30); glass with ~45.7 wt% SiO2 occurs in semi- continuous shock veins up to 50 mm wide; some terrestrial weathering products are present in fractures, but primary assemblage is essentially unaltered. Oxygen isotope compositios (R. Clayton, UChi): d18O =3D +5.63 = =89,
d17O =3D +2.92=89. Bulk composition (in wt%, E. Jarosewich, SI): SiO2 =3D= 44.7;
TiO2 =3D 3.08; Al2O3 =3D 8.74; FeO =3D 23.0; MnO =3D 0.33; MgO =3D 8.45; = CaO =3D 10.9;
Na2O =3D 0.37; K2O =3D 0.11; H2O =3D 0.06. Specimens: type specimen, ~5-6= g,
contact T. Bunch, NAU; 1.1 g plus thin section, UHaw; main mass, 260 g, Radomsky.
