E&PS_WU_logo.jpg

 

Lunar Meteorite

Northwest Africa 4734 & 10597
(paired stones)

Morocco

 

The pieces of Northwest Africa 4734
(photo credit: Albert Jambon)

 

A 33-g stone, the one nearest the loupe in the top photo. Thanks to Tim Heitz for the sample.
(photo credit: Randy Korotev)

 

Note the similarity of the fusion crust to that of the LAP basalts from Antarctica
(photo credit: Randy Korotev)

 

Chips of basalts LAP 04841 (left) and NWA 4734 (right), same scale (millimeter ticks)
(photo credit: Randy Korotev)

lm_nwa10597_WH1_m.jpg
lm_nwa10597_WH2_m.jpg

Two views of Northwest Africa 10597. Click on image for enlargement.
(photo credit: Weibiao Hsu)

lm_nwa10597-WH_m.jpg

Sawn face of NWA 10597. Click on image for enlargement.
(photo credit: Weibiao Hsu)

lm_nwa10597-BSE_WH_m.jpg

Backscattered electron (BSE) image of NWA 10597. Click on image for enlargement.
(photo credit: Weibiao Hsu)

 

from The Meteoritical Bulletin, No. 93, Meteoritics & Planetary Science 43, 571–632 (2007)

Northwest Africa 4734

Rissani, Morocco
Find: October 2006
Mass: 477 g

Achondrite (lunar)

History: Two pieces were purchased from nomads in Erfoud, Morocco in October 2006 and February 2007.

Physical characteristics: A. Habibi purchased two pieces, with a total mass of 477 g, in Rissani, Morocco, and several other pieces of the same stone totaling 895 g are with M. Oumama in Rissani, Morocco. Dull black/brown fusion crust nearly complete and inside slightly tarnished where absent. It is a gray, coarse grained, pristine magmatic rock consisting of millimeter-sized phenocrysts, mainly of pyroxene and plagioclase.

Petrography: (A. Jambon, O. Boudouma and D. Badia, UPVI). The texture is best described as shergottite-like. Pyroxene grains are highly fractured while plagioclase laths, partly transformed to maskelynite, are only affected by a small number of fractures. Silica and silica-feldspar glass are minor components. A few patches of impact melt are also observed. Ilmenite, baddeleyite, zirconolite, tranquilityite, pyrrhotite and metal. Fayalite associated with silica probably results from the dissociation of iron rich pyroxene. Modal mineralogy (vol %): Cpx 50, Plagioclase + Kspar 32, silica + glass 7.5, opaques (ilmenite, Ti-magnetite, pyrrhotite) + fayalite 7, voids + fractures 3.

Geochemistry: Mineralogy by EMP and SEM. (Trace and major element analyses ICP-MS and ICP-AES, J-A Barrat, UBO). Pyroxene grains are complexly zoned (En65Fs21Wo13 to En2Fs83Wo15; FeO/MnO = 78 [average]). A few compositions correspond to pyroxferroite. Plagioclase is normally zoned from An75-91 (average An89) with minor olivine (Fa80-95). Chondrite normalized REE pattern with an enrichment of 53 (La) to 40 (Yb). Trace element pattern with negative anomalies of Sr and Eu. Interstitial glass is high in silica (75 wt%) and contains microcrysts of K-feldspar with a significant celsian component. The chemistry, major and trace elements, is identical to NWA 032-479-773 and LAP 02205-02224-02226-02234-02436-03632. The texture is very similar to that of the LAP specimens. The very low abundance of olivine and the relative abundance of silica in NWA 4734 are the main differences beside the grain size and the slightly different composition of the major phases.

Classification: Achondrite (lunar); extensive shock.

Type specimens: A total of 20 g of sample and one polished section is on deposit at UPVI. Mbarek Ait Elkaid hold the main masses.

 

from The Meteoritical Bulletin, No. 105

Northwest Africa 10597

Morocco
Purchased: 2016 Feb
Mass: 350 g

Classification: Lunar meteorite (basalt)

History: Purchased by Ke Zuokai in Feb. 2016 at Tucson mineral show from an anonymous Moroccan dealer.

Physical characteristics: A single stone with a complete fresh fusion crust.

Petrography: The meteorite is a medium-grained unbrecciated basalt composed of elongate, zoned pyroxene (up to 1 mm) grains and plagioclase (up to 1.2 mm) laths. Olivine phenocrysts are up to 350 µm, and commonly have inclusions of hercynite, Ti-Al-rich chromite, pigeonite or rarely augite with intergrowth of Na-rich glass. Most pyroxene grains are pigeonite with a minor amount of augite. A few pigeonite grains have augite rims. Plagioclase  is partly converted to maskelynite. Late-stage mesostasis is composed of silica, Fe-rich olivine, Fe-rich pyroxene, K-rich glass, ilmenite, pyrrhotite, baddeleyite, and elongate, skeletal apatite and merrillite. Other opaque phases include chromite, Ti-rich chromite, troilite, ulvöspinel, tranquillityite, zirconolite and a few FeNi metal. Shock veins and impact melt pockets are present. Mineral modes (vol%): olivine = 6, pyroxene =52, plagioclase = 32, silica=3, ilmenite = 4, mesostasis + impact melt = 3.

Geochemistry: Plagioclase, An85.1±2.3Or0.4±0.3 (An78.5-87.8Or0.2-0.8, n=20); olivine zoned from Fo58.2-49.9 (cores) to Fo36.6-40.7 (rims) (Fa46.5-93.1, n=13; FeO/MnO = 81.9-106.8, average: 91±7); zoned pigeonite, core En57.7-51.6Wo8.9-16.8, rim En7.2-22Wo20.2-31.5 (Fs28.5-79.6Wo10.1-25.5, n=23), and augite, Fs21.3-52.5Wo28.4-39.3 (Wo32.9-36.2 En11.9-38.8, n=9), with pyroxene FeO/MnO = 30.8-81.9, average: 60±10; mesostasis olivine and pyroxene, Fo2.3-13.5 and En1-3Wo14-17. Chemical compositions (wt.%) of fusion crust: MgO 7.0, FeO 23.5, Al2O3 7.9, SiO2 47.4, CaO 10.6, TiO2 3.5.    

 

Randy Says…

NWA 4734/10597 is one of the few unbrecciated basalts.  The meteorite is compositionally and texturally identical to LAP basalts from Antarctica and likely launch paired. NWA 10597 is probably one of the “several other pieces of the same stone [NWA 4734] totaling 895 g…”

 

More Information

Meteoritical Bulletin Database

NWA 4734 | 10597

References

Chennaoui Aoudjehane H. and Jambon A. (2008) First evidence of high pressure silica: Stishovite and seifertite in lunar meteorite Northwest Africa 4734 (abstract). 71st Annual Meeting of the Meteoritical Society, abstract no. 5058, Meteoritics & Planetary Science 43, A32.

Elardo S. M., Shearer C. K. Jr., Fagan A. L., Neal C. R., Burger P. V., and Borg L. E. (2012) Diversity in low-Ti mare magmatism and mantle sources: A Perspective from lunar meteorites NWA 4734, NWA 032, and LAP 02205 (abstract). In Lunar and Planetary Science XLIII, abstract no. 2648, 43rd Lunar and Planetary Science Conference.

Elardo S. M., Shearer C. K., Fagan A. L., Borg L. E., Gaffney A. M., Burger P. V., Neal C. R., and McCubbin F. M. (2013) The origin of young mare basalts inferred from lunar meteorites NWA 4734, NWA 032, and LAP 02205 (abstract). In 44th Lunar and Planetary Science Conference, abstract no. 2762.

Elardo S. M., Shearer C. K. Jr., Fagan A. L., Borg L. E., Gaffney A. M., Burger P. V., Neal C. R., Fernandes V. A., and McCubbin F. M. (2013) The origin of young mare basalts inferred from lunar meteorites Northwest Africa 4734, 032, and LaPaz Icefield 02205. Meteoritics & Planetary Science 49, 261–291. doi: 10.1111/maps.12239

Fernandes V. A., Korotev R. L., and Renne P. R. (2009) 40Ar-39Ar ages and chemical composition for lunar mare basalts: NWA 4734 and NWA 4898 (abstract). In Lunar and Planetary Science XL, abstract no. 1045, 40th Lunar and Planetary Science Conference.

Fernandes V. A. S. M., Fritz J. P., Wünnemann K., and Hornemann U. (2010) K-Ar ages and shock effects in lunar meteorites (abstract). EPSC Abstracts, Vol. 5, EPSC2010-237.

Hsu W. and Wu Y. (2016) NWA 10597 — A new unbrecciated mare basalt (abstract). 79th Annual Meeting of the Meteoritical Society, abstract no. 6042.

Jambon A. and Devidal J.-L. (2009) Monazite dating of lunar meteorite NWA 4734 (abstract). 72th Annual Meeting of the Meteoritical Society, number 5006.

Korotev R. L., Irving A. J., and Bunch T. E. (2008) Keeping up with the lunar meteorites – 2008 (abstract). In Lunar and Planetary Science XXXIX, abstract no. 1209, 39th Lunar and Planetary Science Conference.

Korotev R. L., Zeigler R. A., Irving A. J., and Bunch T. E. (2009) Keeping up with the Lunar Meteorites — 2009 (abstract). In Lunar and Planetary Science XL, abstract no. 1137, 40th Lunar and Planetary Science Conference.

Miyahara M., Kaneko S., Ohtani E., Sakai T., Nagase T., Kayama M., Hishido H., and Hirao N. (2013) High-pressure polymorphs of silica in NWA 4734. Antarctic Meteorites XXXVI, Papers Presented to the Thirty-Sixth Symposium on Antarctic Meteorites, p. 52, Tokyo.

Rochette P., Gattacceca J., Ivanov A. V., Nazarov M. A., and Bezaeva N. S. (2010) Magnetic properties of lunar materials: Meteorites, Luna and Apollo returned samples. Earth Planet. Sci. Lett., doi:10.1016/j.epsl.2010.02.007.

Xu L., Lin Y. T., Hofmann B. A., Gnos E., and Ouyang Z. Y. (2012) The origin of metal particles in lunar meteorites (abstract). 75th Annual Meeting of the Meteoritical Society, abstract no. 5247.

Wang Y. and Hsu W. (2010) SIMS Pb/Pb dating of Zr-rich minerals from NWA 4734 and LAP 02205/02224: Evidence for the same crater on the Moon (abstract). 73th Annual Meeting of the Meteoritical Society, abstract no. 5024. Lunar and Planetary Institute.

Wang Y. and Hsu W. (2016) Shock-induced metamorphism in the lunar meteorite Northwest Africa 4734 (abstract). 79th Annual Meeting of the Meteoritical Society, abstract no. 6337.

Wang Y., Hsu W., Guan Y., Li X., Li Q., Liu Y., and Tang G. (2012) Petrogenesis of the Northwest Africa 4734 basaltic lunar meteorite. Geochimica et Cosmochimica Acta 92, 329-344.

 

 

Back to: Lunar Meteorites | List of Lunar Meteorites | Top of Page

 


Prepared by
: Randy L. Korotev
 
Department of Earth and Planetary Sciences
Washington University in St. Louis

Please don't contact me about the meteorite you think you've found until you read this and this.


e-mail
korotev@wustl.edu

Last revised: 28-June-2016