[meteorite-list] Meteorites and sulfurous odors

[Piper R.W. Hollier]

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