Northwest Africa 5764 meteorite (NWA 5764), Northwest Africa Meteorites
This page is currently not sponsored. Click here to sponsor this page.
|Non-native locality type:||Meteorite|
|Meteorite Class:||LL6 chondrite meteorite|
|Meteoritical Society Class:||LL6|
|Metbull:||View entry in Meteoritical Bulletin Database|
Ordinary Chondrite, brecciated (LL6; S2-S4; W1)
Found, 2003; 502 g
Northwest Africa 5764 (NWA 5764) is an unusual LL6 ordinary chondrite which contains prominent L4 clasts. The mildly weathered stone still retains ~80% of its original fusion crust. Dominant and largely equilibrated Fe-rich olivine (Fa~31) and orthopyroxene (Fs~26) within the groundmass are characteristic of the relatively very low (LL) ordinary chondrite group. The LL6 groundmass lithology consists of both light and dark clasts, but it also contains numerous exotic dark L4 clasts (Fa26;Fs22) which are several centimeters in size. These L4 clasts are darkened by ubiquitous and widespread tiny sulfides (troilite is specifically noted) within both chondrules and groundmass. Olivines and pyroxenes are cemented by albitic plagioclase (and feldspathic glass). Fe-Ni metal is mostly martensitic. Tetrataenite is present on the edges of some Fe-Ni aggregates within both the LL6 groundmass and the L4 clasts. There are a number of similarities between the LL6 and L4 lithologies. However, the shock level of the L4 clast is somewhat higher (S4). Kamacite displaying deformed Neumann bands and metallic copper are observed within the L4 clast as well as a number of associated adjoining shock veins.
The Gattacceca et al. (2017) article provides detailed arguments for concluding that the common U-He age (~2.9 Ga) for the two NWA 5764 lithologies and almost identical average CRE ages (36.5 ± 5.8 Ma [LL4]; 36.7 ± 5.7 Ma [LL6]) indicate that the two lithologies were probably joined soon after the end of ordinary chondritic metamorphism. These authors conclude by noting that incorporation of (exotic) large cm-sized clasts from one distinct ordinary chondrite group into another is quite rare. (The authors cite Dimmitt, St. Mesmin , and a less studied Glanerbrug meteorites.)
The actual recovery site in Algeria has not been provided to the Meteoritical Society.
4 valid minerals.
Meteorite/Rock Types Recorded
Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Alexeev, V.A. (1998) Parent bodies of H and L chondrites: Times of catastrophic events. Meteoritics & Planetary Science 33(1): 145-152. (Jan 1998).
Leya, I., Graf, Th., Nishiizumi, K. & Wieler, R. (2001) Cosmic-ray production rates of helium, neon and argon isotopes in H chondrites based on chlorine-36/argon-36 ages: Meteoritics & Planetary Science 36(7): 963-973. (July 2001).
Weisberg, M. K. et al. (2009) Meteoritical Bulletin, No. 96, September 2009: Meteoritics & Planetary Science 44 (9): 1355-1397. (Sept 2009).
Gattacceca, J., Bourot-Denise, M. & Lenssen (2009) NWA 5764: The First LL-L Chondrite [pdf.#5085]: Meteoritics & Planetary Science 44 (Suppl): A75. (July 2009).
Gattacceca, J. et al. (2017) Young asteroid mixing revealed in ordinary chondrites: The case of NWA 5764, a polymict LL breccia with L clasts: Meteoritics & Planetary Science 52 (11): 2289-2304. (Nov 2017).