As
Earth
scientists
we
are
aware
that
objects
(sometimes
really
big
objects)
have
impacted
Earth
in
the
past.
As
keen
natural
observers,
often
working
in
pristine,
non-light-polluted
parts
of
our
world
we
have
a
better
than
average
chance
of
seeing
celestial
objects
flash
across
the
sky
but
few
of
us
have
had
the
opportunity
to
get
up
close
and
personal
with
a
recent
impact
site,
However,
this
is
exactly
what
happened
last
Fall
in
a
remote
part
of
Peru
near
the
border
of
Bolivia.
At
11:45
on
the
morning
of
September
15th
2007
a
meteorite
landed
about
5
km
from
the
Bolivian
–
Peruvian
border
near
the
village
of
Carancas
in
Peru.
The
site
location
is
shown
in
Figure
1
at
16º
39’
32”
S;
69º
02’
38”
W
and
at
an
elevation
of
3,824m.
The
impact
created
a
moderately
large
crater
about
13
-
14m
(~
45
feet)
in
diameter.
The
rim
of
the
crater
is
between
one
and
two
metres
in
height
and
the
crater
is
at
least
4
m
deep.
The
impact
took
place
on
the
floodplain
of
a
large
river
system.
There
were
reports
of
people
smelling
sulphur
and
stories
of
people
being
ill.
Figure
1:
Location
of
the
Carancas,
Peru,
impact
site
near
the
south
end
of
Lake
Titicaca.
Some
have
theorised
that
noxious
gases
were
released
from
the
meteorite
or
that
the
impact
released
gases
with
arsenic
from
the
water
table.
However,
I
think
a
simpler
explanation
might
be
that
hydrogen
sulphide
was
released
from
organic
debris
trapped
in
the
sediments
around
the
impact
site.
Looking
at
the
detailed
images
available
on
Google
Earth
of
the
area
west
of
the
impact
site
it
appears
that
this
is
a
region
that
may
have
permafrost,
and/or
has
been
recently
glaciated
since
there
are
a
number
of
depressions
that
resemble
kettle
holes
or
thermo-karst
melt
holes.
Michael
Farmer,
a
meteorite
collector
who
visited
the
site
suggested
that
the
meteorite
likely
weighed
about
10
tons
on
impact.
His
site
is
interesting
and
has
some
excellent
images
of
the
impact
site.
Figure
2:
The
Carancas
impact
site
(top)
with
a
fragment
(lower
left).
Note
that
the
“crust”
is
a
resin
coating
used
to
bind
the
specimen
for
thin-sectioning.
It
is
not
an
ablation
rind
frequently
found
in
meteorites.
Thin
sections
illustrating
the
largely
pyroxene/olivine
nature
of
the
chondrite
are
shown
on
the
lower
right.
Material
recovered
by
Peruvian
authorities
show
that
the
meteorite
is
a
chondrite
(stony
meteorite)
with
a
composition
of
about
50%
pyroxene,
20%
olivine
and
10%
feldspar.
The
remainder
is
made
up
of
15%
kamacite
(a
90:10
alloy
of
iron
and
nickel)
and
5%
troilite
(an
end
member
of
the
iron
sulphide
mineral,
pyrrhotite).
The
troilite
end
member
is
rare
in
crustal
rocks
but
is
relatively
common
in
meteorites.
There
were
also
traces
of
chromite
and
native
copper
present.
Specimens
of
the
Carancas
meteorite
are
now
being
sold
for
about
$
US
10/gram.
The
full
scientific
results
of
the
examination
of
this
relatively
unusual
meteorite
have
not
yet
been
released.
Alan
V.
Morgan
