[meteorite-list] Meteorites and sulfurous odors

From: Piper R.W. Hollier <piper_at_meteoritecentral.com>
Date: Fri, 05 Oct 2007 18:51:57 +0200
Message-ID: <6.2.1.2.2.20071003211501.03272e70_at_pop.xs4all.nl>

Hello list,

Ordinary chondrites generally contain around 2% troilite (iron sulfide,
FeS); the thin section made of the Carancas meteorite shows even more,
around 5%. Troilite dissociates at high temperatures (e.g. a hypersonic
impact), releasing hot sulfur vapor, which in turn will oxidize in air to
form sulfur dioxide, a very irritating poison. The sulfurous smell that a
match makes when you strike it is due to sulfur dioxide from sulfur in the
match head oxidizing.

Visitors to the Carancas crater soon after the impact reported a sulfurous
odor, which under the circumstances, a high temperature impact of a
chondrite, is perhaps no big surprise. The symptoms of people who reported
becoming ill at Carancas (irritation of respiratory tract, nausea,
vomiting, stomach pain, dizziness, headache, skin lesions) are consistent
with exposure to sulfur dioxide gas and/or to the sulfurous acid (H2SO3)
that forms when sulfur dioxide dissolves in water.

Sulfur dioxide is more than twice as dense as air and would tend to remain
in the crater under windstill conditions. Furthermore, the gas would
permeate the churned up soil and the fragmented/pulverized remains of the
meteorite and would continue to seep out of the crater walls for hours.
Although the gas would eventually dissipate, the fraction of the gas that
dissolved in water, forming sulfurous acid, could persist in the meteorite
dust found at the crater. If the dust was stored in a closed container
after being collected, it could conceivably cause the "stinging of a
thousand little bees" effect that Randall's wife mentions.

If this meteoroid really did weigh hundreds or even thousands of kilograms
before impact, that would mean that there was quite a lot of troilite
present in the impact event. The impact thus had the potential to produce a
substantial volume of noxious gas and to leave behind more than a trace of
acidic residue.

We cannot entirely reject the possibility that arsenic in the ground water
may also have been a factor. Arsine gas (AsH3) causes many of the same
symptoms as sulfur dioxide (nausea, vomiting, headache) at very low
concentrations of only a few parts per million. But as far as I know there
is only conjecture that there was actually a substantial amount of arsenic
in the ground water at the impact site. Given that we know with certainty
that a sulfur-bearing mineral was present is significant amounts in the
meteoroid and that heating it would release sulfur dioxide gas, that would
seem to be the most logical explanation for the symptoms reported.

It is hard to know what to make of news accounts recently in which supposed
"experts" dismiss reports of noxious odors at Carancas. There are multiple
historical accounts of sulfurous odors being connected with fresh meteorite
falls.

  - The Pleskowitz fall in Bohemia in 1723: meteorite fragments "exhaled a
strong odor of sulfur."

  - The Wold Cottage fall in 1795: "A laborer looked up just in time to see
a black stone emerge from the clouds and plunge into the soil about 30 feet
from where he stood. The ground shook and mud and sod flew up all around
him. Rushing to the spot he found a large stone, warm and smoking and
smelling of sulfur."

  - The fall of the Karakol meteorite (a 2.7 kg LL6 chondrite) in
Kazakhstan in 1840: "At the place of the fall a thin smoke rose. The
Kirghiz were scared and went to the place only half an hour later. A
meteorite was buried into the soil three-fourths of an arshin deep. Later
when we took it out of the soil it was still warm and had a sulfur smell."

  - The Tagish Lake fall in March 2000: "The crumbly, black, porous rock
fragments have charred, pocked surfaces and retain the smell of sulfur." (CNN)

  - The Park Forest, Chicago fall in 2003: Colby Navarro stated, "Plaster
blew all over me and all over the upstairs; then I found the rock," then
added that it was warm to the touch and smelled like the sulfur from
fireworks.

Who can add to this list, with references to the literature of historical
falls and to news reports ... or even just with personal anecdotes?

It would also be useful to hear about sulfurous odors emanating from
recently cut meteorites or arising during the cutting process. From my own
experience, I can relate that Darryl Pitt showed me a slice of Hvittis
(fell in Finland, 1901, EL6) at the meteorite fair in Gifhorn, Germany some
years ago (1999?) and suggested that I sniff it. There was a distinctive
sulfurous odor, similar to the smell that a match makes when you light it,
not especially strong, but nevertheless unmistakable. The catalog of the
Macovich Meteorite Auction at the Tucson mineral show in February 2001
mentions a "smell of sulfur" in the description of a Hvittis specimen,
possibly the same one that I "sampled" in Gifhorn.

Best wishes to all,

Piper
Received on Fri 05 Oct 2007 12:51:57 PM PDT