The only information available about this meteorite is in two
abstracts, one for the 31st Lunar & Planetary Science Conference
(2000) and the other for the 13th Goldschmidt Conference (2003), both
by Dr. Keizo Yanai. The second abstract states that the meteorite
was "found in Antarctica" but no details are given, including
the mass.
The description, mineral chemistry, and bulk composition (only
data
for major elements are provided in the abstracts) are all consistent
with a feldspathic lunar meteorite. For that reason,
I include it in the List.
The meteorite does not have an accepted name because it has not
been submitted
for approval by the Nomenclature Committee of the Meteoritical Society.
"Specimen 1153" is not an "official" meteorite.
A curious chemical feature of the published composition is that
CaO is too high (18.05%) for the Al2O3 concentration
(27.44%). CaO ought to be about 15.9% because CaO/Al2O3
is constant (0.58) among feldspathic rocks of the lunar highlands. High
CaO is a characteristic of hot-desert meteorites that have undergone
terrestrial
alteration (e.g., Korotev et al., 2003). Most lunar meteorites from hot
deserts contain calcium carbonate or calcium sulfate of
terrestrial origin.
Specimen
1153
has a CaO/Al2O3 of 0.66. None
of the feldspathic lunar meteorites collected in Antarctica by ANSMET
or
NIPR
have CaO/Al2O3 greater than 0.59. Also,
the reported concentration of sulfur, 0.61%, is at least 100 times
that
expected for a lunar feldspathic brccia. (I am unaware of any
other published
data for S concentration in feldspathic lunar meteorites. S concentrations
are so low that no one measures them.) Thus, I have to conclude that
the stone contains a few percent gypsum and calcite, unlike any other
lunar meteorites from Antarctica. Until
someone called my attention to the 2003 abstract, I also concluded and
stated
here (Sept. 22, 2005, to Feb. 5, 2007) that
the stone was likely
from a hot desert. If it is from Antarctica, then it must have been found
in an environment, perhaps a glacial moraine or dry valley, where there
were cycles of water accumulation and evaporation.
The Mg/Fe of specimen 1153 is at the low end of the range among feldspathic
lunar meteorites. For this
reason, there is no obvious potential pair among known lunar meteorites.
The only other chemical anomaly is that the reported concentration
of
Na2O is 70% of that typical for a feldspathic lunar
meteorites; this anomaly may reflect an analytical problem, however.
Overall,
"specimen 1153" is compositionally most similar to MAC 88104/5.
revised: 05-Feb-2007
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