Reprinted from METEORITE!
Magazine, Pallasite Press, August 1996
Dr. Richard Herd (right) and
the Forcier brothers.
The St. Robert Stone
by Russell W. Kempton, New
England Meteoritical Services
A dozen cows are in a pasture,
standing in a circle looking downward. Could any of us, in our wildest
thoughts, ever imagine that they would be looking at a freshly fallen meteorite
that only seconds before had plunged into their field?
It is a few minutes before
sunset on June 14, 1994 in eastern Canada. Grazing cows have just witnessed a
shower of meteorites - the 12th recorded fall in Canada - and the beginning of
an event that would set many precedents over the next two years. The pastoral
village of St. Robert, Quebec found itself instantly catapulted into the 20th
Century world of meteoritics, research, and Cultural Property Laws.
Every aspect of the St. Robert
fall is remarkable. The fireball (brightness estimated at -18 magnitude) was
seen over New York, Vermont, New Hampshire, Quebec, and Ontario by thousands of
people. Optical and infrared sensors in Earth-orbit recorded its passage and
multiple detonations were audible in Ottawa more than 200 km from the fireball
endpoint. In Montreal, less than 25 km ground distance from the fireball's
path, windows rattled and buildings shook. Many observers reported a dust cloud
visible for over two minutes after the bolide's transition from fireball to
dark-flight. Strangely however, there are no known photographs or video records
of the event.
Optical and infrared satellite
data provided by the US Defense Department has enabled a consortium of Canadian
researchers to determine many critical aspects of the St. Robert meteorite:
probable azimuth of the ground path, 202 degrees, slope of entry, 58 degrees,
fireball peak magnitude of -18 at a fragmentation altitude of 36 km, and the
fireball end-height of 25 km. The satellite data has also contributed to
preliminary determinations of mass, entry velocity, and orbital
Many residents of St. Robert
gave spectacular accounts of detonations, whistling sounds, the noise of
objects falling through nearby trees, and the dull "thud" of impacts around
them. Denis Racine was mowing his grass when he heard atmospheric detonations
over the sound of his lawnmower. Looking upward, he saw three distinct
contrails or "streamers." Vital Lemay was feeding his foxes when he too was
startled by two to three "bangs," felt the ground shake and heard the low
"thud" of impact.
2.3 kg meteorite inside the
But perhaps the most
interesting account is that of Stephane Forcier who saw his cows "standing in a
circle staring at something." Walking into the center he found a hole in the
soft soil about 15 cm in diameter and 20 cm deep. Reaching into the hole,
Forcier extracted a 2.3 kg "scorched-looking" rock the size of a cantaloupe
that was cold!
Forcier informed the local
police of his find and the following day it was confirmed to be a meteorite by
Dr. Richard Herd of the Geological Survey of Canada. Herd, Curator of Canada's
Collection and Principal
Investigator of the St. Robert Fall moved quickly with the 2.3 kg mass. He
hand-carried the meteorite to Battelle Laboratory in Richland, Washington, USA
where cosmogenic nuclide measurements (the measurement of various isotopes of
aluminum, sodium, etc.) began immediately. Analysis of these short-lived,
cosmically-induced changes in the chemistry of a meteorite can reveal valuable
information about its recent history.
Isotopes of the element cobalt
(cobalt-60 or 60Co) with a half-life of 5.272 years and cobalt-56
(56Co) with a half-life of 77.7 days can be used to constrain a
minimum size of the pre-atmospheric mass if measured shortly after arrival upon
the Earth. Levels of 60Co and 56Co in meteorites are
inversely proportional to cosmic-ray shielding and thus become a function of
depth within the meteoroid. Within 68 hours of the fall these time-critical
measurements began - the shortest time on record for any fall.
The levels of 60Co
and 56Co measured in St. Robert were low and imply a sizable
pre-atmospheric body of 700 kg for the lower limit and 4000 kg for the upper
limit. However, theoretical modeling of the fireball trajectory, observed
fragmentation, and acoustic measurements of the blast wave have refined this
number to 1,500 to 2,000 kg before atmospheric entry. Given the entry velocity
of approximately 12 km/sec, as obtained from satellite data, there should be a
lot of this material on the ground somewhere.
The Business of
The monetary value of
meteorites has risen dramatically in recent years. The number of collectors and
educational institutions interested in acquiring specimens increases yearly
while the available supply of meteorites does not. With any new fall or find,
competition among dealers usually results in a bidding war that drives the
price upward making it difficult for institutions with limited funds to acquire
When meteorites fall on
private property in Canada they belong to the property owner. The owner is free
to either sell or retain the meteorite if they so chose. However, since
meteorites are considered to be cultural property in Canada their export
requires a permit. Interestingly, this law seems to have a "leveling effect"
that works to the benefit of all by slowing down the process. The permit
application time can be lengthy allowing time for the owners to explore various
options of sale. Bidding wars between dealers that can become "heated" raising
prices to unreasonable levels, are "cooled" by the uncertainty of when and if a
meteorite will become available for export. Institutions such as the Geological
Survey of Canada (GSC) can use this time to compete with the private sector by
raising funds or helping the owner to explore what may be highly advantageous
tax credits from the government if a meteorite is donated to a cultural
institution. This is exactly what happened with two of the larger fragments of
6.552 kg specimen of St. Robert
Richard Herd, negotiating on
behalf of the GSC, purchased from Stephane Forcier the 2.297 kg meteorite
spotted by his cows for $10,000 Canadian, and recently acquired the largest
mass, 6.552 kg, from another individual through donation and tax credits. Both
specimens are on display at the National Collections in Ottawa.
The St. Robert meteorite has
been typed as an H5 chondrite and the first stony meteorite to be found in
Quebec. Studies of the fall indicate the total fall mass of meteorites larger
than 55 g to be between 65 kg to 130 kg distributed through 120 to 240
fragments. Yet, as of this writing, only 20 fragments of St. Robert totaling
25.4 kg have been recovered within an ellipse-shaped strewn field measuring 8 x
3.5 km. This leaves approximately 40 to 100 kg still undiscovered in this
populated area of southeastern Quebec. But where? Why haven't more been found?
A veritable army of dedicated researchers and townspeople have painstakingly
combed the area.
Well, since three quarters of
the strewn field is covered with corn and grain fields or cow pastures, a
reasonable number are probably imbedded in the soft soil hindering their
efforts. Hopefully though, the seasonal freeze/thaw cycles will push several
meteorites to the surface over the winter months making them easier to locate
when the ground thaws. Perhaps I'll go there in the spring, not to try any
sophisticated detection techniques, just simply to watch the cows...
The author expresses his
sincere thanks to Gina Le Cheminant and Richard Herd of the Canadian National
Collections, Geological Survey of Canada for their valuable assistance,
professionalism, and knowledge. I would also like to recognize the authors of
"The Fall of the St. Robert Meteorite," Meteoritics & Planet. Sci.,
July 1996, Peter Brown, Alan R. Hildebrand, Daniel W.E. Green, Denis Page,
Cliff Jacobs, Doug Revelle, Edward Tagliaferri, John Wacker, and Bob
Photographs courtesy of Dr.
Author's note: Canadian
law regarding meteorites is very clear. In Canada, meteorites that fall on
private property belong to the property owner and may be held or sold by the
owner. However, meteorites are considered Cultural Property and require an
export permit to be taken or shipped out of Canada. Exporting without a permit
even temporarily is illegal and potentially a criminal offense. For additional
information readers should contact Canadian Customs or Dr. Richard Herd at the
Geological Survey of Canada in Ottawa,
Canada KIA OE8.
Russell Kempton is the
Director of New England Meteoritical Services, based in Mendon, Massachusetts,
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