Lunar meteorite MET 01210 (hereafter referred to as MET) is a 22.8 g breccia collected during the 2001 field season in the Meteorite Hills, Antarctica. Although initially classified as an anorthositic breccia, MET is a regolith breccia composed predominantly of very-low-Ti (VLT) basaltic material. Four other brecciated lunar meteorites (NWA 773, QUE 94281, EET 87/96, Yamato 79/98) with a significant VLT basaltic component have been identified. We present here the petrography and bulk major element composition of MET and compare it to previously studied basaltic lunar meteorite breccias

Haskin, L. A.

Jolliff, B. L.

Korotev, R. L.

Zeigler, R. A.

NASA Technical Reports Server

PETROGRAPHY OF LUNAR METEORITE MET 01210, A NEW BASALTIC REGOLITH BRECCIA.  *R. A. Zeigler, R. 
L. Korotev, B. L. Jolliff, and L. A. Haskin. Dept. of Earth and Planetary Science, Washington University, 1 Brook-
ings Dr., Campus Box 1169, St. Louis MO, 63130; *zeigler@levee.wustl.edu. 
 
Introduction:  Lunar meteorite MET 01210 (here-
after referred to as MET) is a 22.8 g breccia collected 
during the 2001 field season in the Meteorite Hills, 
Antarctica. Although initially classified as an anortho-
sitic breccia [1], MET is a regolith breccia composed 
predominantly of very-low-Ti (VLT) basaltic material. 
Four other brecciated lunar meteorites (NWA 773, 
QUE 94281, EET 87/96, Yamato 79/98) with a signifi-
cant VLT basaltic component have been identified [2-
3]. We present here the petrography and bulk major-
element composition of MET and compare it to previ-
ously studied basaltic lunar meteorite breccias. 
Methods: We determined mineral compositions by 
electron microprobe analyses (EMPA) on a polished 
thin section of MET using a JEOL 733 Superprobe at 
15 keV accelerating voltage, 20-40 nA beam current, 
and a 1-20 µm beam size. The bulk major-element 
composition of MET is estimated based on EMPA 
analyses on the fusion crust of MET (Table 1). 
Results:  MET is a lunar breccia composed pre-
dominantly of lithic and mineral clasts set in a glassy 
matrix (Fig. 1f). There are no obvious regolith compo-
nents, e.g. spherules or agglutinates, apparent in MET. 
A narrow vesicular fusion crust is present along one 
edge of MET. Most lithic clasts in MET are either 
“coarse” grained VLT basalt-gabbro clasts or very fine-
grained granulite clasts, with a few symplectite grains 
also present. The basalt-gabbro clasts (Fig. 1a-b) are 
composed mainly of pyroxene and plagioclase with 
lesser amounts of olivine and almost no detectable Fe,Ti 
oxides. The pyroxene grains range wildly in composi-
tion (Fs12-61Wo3-39; Fig 2a), are commonly well equili-
brated, and in some places have 1-2 µm exsolution. The 
olivine (Fo37-76; Fig 2b) and plagioclase (An90-97) grains 
also range in composition, neither showing appreciable 
zoning trends. Several symplectite grains, silica-
fayalite-hedenbergite intergrowths resulting from the 
break-down of pyroxferroite, are observed (Fig. 1c). 
The granulitic clasts (Fig 1d-e) are composed of plagio-
clase (An93-98) and glass with very few pyroxene and 
olivine grains present (Fig. 2a). The granulite clasts are 
highly feldspathic, with >80% modal plagioclase. 
 Mineral clasts in MET are predominantly pyroxene, 
with lesser amounts of plagioclase and olivine. The py-
roxene clasts have a wide range of compositions (Fs25-
82Wo6-39; Fig 2c) and are commonly exsolved (1-2µm). 
The olivine clasts also range widely in composition 
Figure 1: Back-scattered electron images of various lithic clasts in MET (a-e) and the glassy matrix (f). Plag = plagioclase, pyx = 
pyroxene , olv = olivine. (a) Basaltic lithic clast. Scale bar = 300 µm. (b) Gabbroic lithic clast. Scale bar = 300 µm. (c) Symplec-
tite grain. Brightest phase is fayalite, middle brightness is pyroxene, and silica is the darkest phase. Scale bar = 300 µm. (d) 
Granulitic clast with a plagioclase hosting small amounts of glass and olivine (bright blebs). Scale bar = 150 µm. (e) Granulitic 
clast with larger proportion of glass. Scale bar = 150 µm. (f) Close up view of the matrix. Scale bar = 80 µm. 
pyx 
pyx plag 
Basalt 
clast 
Symplectite 
Grain 
Gabbroic 
Clast 
Granulite 
Clast 
Granulite 
Clast 
Glassy 
Matrix 
(a) (b) (c) 
(f) (e) (d) 
pyx 
olv 
plag 
Table 1: Bulk composition of MET
SiO2 44.8 Cr2O3 0.19 MgO 5.97
TiO2 1.58 FeO 16.2 CaO 13.6
Al2O3 17.0 MnO 0.26 Na2O 0.26
All values in wt%. K2O (not listed) is <0.2 wt%.
Lunar and Planetary Science XXXVI (2005) 2385.pdf
https://ntrs.nasa.gov/search.jsp?R=20050182075 2019-08-29T20:07:48+00:00Z
(Fo44-98; Fig 2d) with a high proportion of fayalite ob-
served (55% of olivine clasts have a composition 
<Fo10). The plagioclase clasts are typically highly frac-
tured, are not maskelynitized, and almost all have a 
composition in the range An92-96 (four grains have  
compositions in the An85-88 range). A few irregularly 
shaped glass clasts are observed, as well as one large 
glass grain that appears to have undergone silica vola-
tilization (similar to the HASP glasses of [4]). Trace 
amounts of ilmenite, ulvöspinel, troilite, Fe,Ni metal 
clasts are also observed. 
The bulk composition of MET is ferroan (Mg’ of 
40), moderately Fe-rich and Al-rich (16 and 17 wt% 
respectively), and relatively low in TiO2 (1.6 wt%). The 
normative composition of MET is 48% plagioclase 
(An95), 22% orthopyroxene, 19% clinopyroxene, 8% 
olivine, and 3% ilmenite. 
Discussion: Despite the lack of spherules and rec-
ognizable agglutinates, the presence of a vesicular fu-
sion crust (typically attributed to escaping solar wind 
implanted gases [5-6]) as well as reworked granulite 
clasts indicates that MET is a regolith breccia, albeit a 
very immature one [7]. Also, our chemical analysis of 
the meteorite [8] yielded 25 ppm Zn, a high value which 
is more consistent with a regolith breccia than an im-
pact-melt breccia [9]. 
The meteorite contains both basaltic lithic clasts 
(e.g., the symplectite grains, the clast in Fig. 1a) as well 
as somewhat deeper seated, hypabyssal gabbroic lithic 
clasts (e.g., the clast in Fig. 1b). The basaltic clasts are 
typically more ferroan, have less well equilibrated py-
roxene, and typically lack the exsolution observed in the 
hypabyssal clasts (Fig. 2a). The compositional range in 
the mineral clasts is similar to the compositional range 
seen in the constituent minerals of the lithic clasts. The 
mineral clasts do show a greater variety of compositions 
and are somewhat more ferroan on average than the 
lithic clasts, however.  
The basaltic and gabbroic lithic clasts in MET are 
clearly VLT, all have less than 0.6 wt% TiO2 (typically 
much less) based on modal recombination. The bulk 
TiO2 concentration of MET (1.6 wt%) is right at the 
border of very-low-Ti and low-Ti lunar basalts, how-
ever. This excess TiO2 is present as small ilmenite and 
ulvöspinel clasts. The bulk major-element composition 
of MET (e.g., 16 wt% FeO) is consistent with it being 
composed predominantly of basaltic material. The only 
material in MET with an obvious highlands provenance 
are the granulitic clasts, which with >80% modal pla-
gioclase would be difficult to produce from reworked 
basaltic material. 
In detail, the trace-element geochemistry of MET 
appears to preclude any obvious connection to the pre-
viously studied lunar meteorite basaltic regolith brec-
cias [8], all of which (except NWA 773) are likely 
source-crater paired [2].  Many of the petrographic fea-
tures observed in MET are also observed in the previ-
ously studied basaltic regolith breccias, however. For 
example, all of the lunar meteorite basaltic regolith 
breccias have a basaltic component that is VLT, all 
have pyroxene and olivine compositions spanning a 
similar range, all have relatively coarsely exsolved py-
roxene (~2 µm), and most contain symplectite grains 
[3,9-10]. One must be careful not to over interpret 
petrographic similarities, particularly in breccias, how-
ever, as chemical composition is a much more diagnos-
tic tool for pairing meteorites than petrography. 
References: [1] Satterwhite et al. (2004) Antarct. Met. 
News. 27 (1). [2] Korotev R. L. et al. (2003) Antarct. Met. 
Res. 16, 152–175. [3] Warren G. H. and Kallemeyn G. W. 
(1991) Proc. NIPR Symp. Antarct. Meteorites 4, 91-117. 
[4] Naney et al., (1976) PLPSC 7, 155-184. [5] Zeigler et al., 
(2004) LPSC XXXV, abstract 1978. [6] Korotev et al., 
(2003a) GCA., 67, 4895-4923. [7] Stöffler D. et al. (1980) 
Proc. Conf. Lunar Crust, 51-70. [8] Korotev R. L. et al. 
(2005) This Volume. [9] Haskin L. A. and Warren P. H. 
(1991) Lunar Chemistry. In Lunar Sourcebook pp. 357-474, 
[10] Jolliff B. L. et al. (1998) MAPS, 33, 581-601. [11] Arai 
T. et al. (1996) MAPS 31, 877-892. 
Acknowledgements: We would like to thank Gretchen 
Benedix for her help with the EMPA. This work was funded 
by NASA grant NNG04GG10G (L. Haskin). 
Figure 2: Pyroxene quadrilaterals showing the composition of 
the MET pyroxenes in the lithic clasts (a) and the mineral clasts 
(b). (a) Each type of lithic clast (e.g, basaltic clast) is a different 
color, with individual clasts of a given type shown as different 
symbols. The compositions of olivine in the lithic clasts are 
shown along the bottom axis. (b) The average composition of 
each pyroxene mineral clast (1 to 5 spots per grain, average of 3) 
are shown in the red points. Each set of colored triangles corre-
sponds to an individual analysis on an exsolved pyroxene clast. 
The composition of olivine mineral clasts is shown along the 
bottom axis. 
Hd
FsEn
Di
Fs
Hd
En
Di
Lithic clasts 
Mineral clasts 
Gabbroic 
Clasts 
Basaltic 
Clasts 
Symp 
Pyx 
Symp 
Bulk 
Symp 
Olv 
Olv comps 
Olv comps 
Exsolved 
pyroxene 
grains 
Granulite Clasts 
Lunar and Planetary Science XXXVI (2005) 2385.pdf


Petrography of Lunar Meteorite MET 01210, A New Basaltic Regolith Breccia

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