Geology Reference
In-Depth Information
,5
ALH A81005
Stage I processing
1982
,0
,2
,1
Clasts
,0
Clast
1 cm
,1
,2
Figure 3.6.
Stage I processing of ALH A81005 which generated splits 1, 2, and 5. Top photo is NASA S82-35865, and bottom is
S82-35867.
Mars until the early 1980s. This sample was originally
7.9 kg, contains multiple lithologies, and has been avail-
able to allocate to the scientific community with many
kilograms of material still remaining. The challenges of
truly small and rare samples are perhaps best illustrated
by the case of the small shergottite QUE 94201 (Plate 71).
This sample was originally 12 g and of a rare and inter-
esting lithology, and thus it has not been possible to allo-
cate many subsamples to the community. It has been
protected by a regular and strict review process whose
aim is to preserve this sample for posterity as best as pos-
sible. The first U.S. Antarctic nakhlite, MIL 03346
(Plate 74), was announced in 2004 and immediately
received an enormous amount of interest. This large
sample was subdivided for allocation to 50 individual
studies and continues to provide to a large Mars science
community much as EET A79001 has, except that the
interest has been in a much more compressed period of
time. Finally, the CR2 chondrites have a growing interest
because they harbor a diverse collection of components
informing a broad range of early solar system research.
The CR2 chondrites have become more and more
popular with time, even since their earliest appearance in
the collection in the 1980s, and now are perhaps the most
popular sample type in the collection, with requests sur-
passing those for lunar and martian meteorites. These
five case studies illustrate the benefits of curating a
diverse collection with the approaches developed and
refined since 1980.
3.3.1. ALH A81005: First Lunar Meteorite (Plate 64)
On January 17, 1982, an interesting 31.39-g achondrite
was found in the Allan Hills icefield (Figure 3.6). It had a
50% thin, tan-green fusion crust, and the exposed interior
exhibited numerous white to grey breccia fragments. The
ANSMET team had found what later became Allan Hills
(ALH) A81005, the first recognized meteorite from the
Moon (Figure 3.6). This sample was of historic signifi-
cance not only because it was the first lunar meteorite,
but it became a great piece of evidence in favor of dynamic
arguments that fragments of the Moon and Mars could
be delivered to the Earth after being ejected from their
parent bodies during an impact event [e.g.,
Marvin
, 1983;
Marvin
, 2014 (this volume);
Korotev and Zeigler
, 2014
(this volume)]. The possibility that this meteorite repre-
sented material not sampled by the
Luna
or
Apollo
mis-
sions led many scientists to request pieces for detailed
study. The meteorite was fairly small, so the MWG
delayed their recommendation to ensure that distribution
