Geology Reference
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and a nonexplosive impact on the Earth. This identifies it
as the only known iron meteorite showing evidence of a
diamond-forming impact in space [
Clarke Jr
., 1982, p. 51].
Unlikely as it seems, this iron gave rise to some second
thoughts about Canyon Diablo: Could its diamonds be
preterrestrial? Was Meteor Crater volcanic after all? No,
it was not. That yawning crater, nearly a mile wide and
surrounded by large fragments of an iron meteorite, bears
testimony to a powerful diamond-producing impact on
the Earth. ALH A77283 shows us that an impact in space
also can create diamonds in irons.
1.7.2. Repercussions from Japan
At the end of the 1977-1978 field season, all the meteor-
ites were shipped to NASA/JSC for processing. But nobody
had thought to inform Takesi Nagata of this new arrange-
ment. So when Keizo Yanai arrived home without Japan's
half of the meteorites, Nagata raised a storm. Although it
seemed to others that Nagata surely would approve of this
effort to keep the meteorites uncontaminated, nationalism
evidently outweighed science when he realized that he had
not been consulted. It took a face-to-face meeting in
Washington with Edward Todd, the Director of NSF's
Division of Polar Programs, to win his agreement, as long
as (1) the United States promised not to circulate any pre-
liminary descriptions of meteorites before Japan received
its share, and (2) a Japanese member was present when the
collection was opened. That promise was easily fulfilled
by inviting Keizo Yanai to be present at JSC during the
opening and distribution of that season's meteorites.
Figure 1.4a.
Iron ALH A77283.
1.8. BECOMING A MEMBER OF ANSMET
By then, I had developed a yearning to go to Antarctica.
At the NSF meeting on 11 November 1977 there had
been talk of maybe sending several field parties each
season. So I asked Mort Turner about submitting pro-
posals, and he loaded me with maps, forms, and booklets.
However, when I checked back with him, he said,
“Realistically, we won't be sending more than one team a
year; call up Bill Cassidy and ask to join his team.”
I had known Bill for years. In fact, he recently had writ-
ten a favorable review of a paper I had submitted for pub-
lication. However, it certainly did no harm to my cause to
call Bill and be able to say, “Mort Turner told me to call
you and ask to join your team in Antarctica.” After we
talked awhile, Bill agreed to take me the next season:
1978-1979.
At about that time, Cassidy was formulating his policy
on choosing team members. First, he always would take a
crevasse expert. They are the most essential members of
the teams. Next, he would look for senior people actively
involved in meteorite research, including Europeans.
Figure 1.4b.
A polished and etched slice of the iron. Minute
grains of diamond and lonsdaleite occur within inclusions such
as the dark one at lower right.
In this, its second season, ANSMET discovered a
unique iron, ALH A77283, which measured about 16 × 16
× 12 cm and weighed 10.5 kg (Figure 1.4a). It proved to be
a carbon-rich octahedrite similar in composition to
Canyon Diablo. That seemed simple enough until its
inclusions of troilite-carbon-schreibersite-cohenite were
found to contain carbonado-like material rich in minute
diamonds and lonsdaleite (Figure 1.4b)! Had the iron
smashed into the ground with enough force to form tiny
diamonds? No, because the meteorite had a heat-altered
ablation zone along one side of it, indicating that it had
had an uninterrupted passage through the atmosphere
