Hi Piper,
Interesting points. I have not seen the original Sears article myself, but
Marvin mentions that Sears thought that meteorites contain too little
troilite to generate the sufurous odor. No mention of other sufur compounds
though.
On the other hand, I know from my chemical safety and health experience that
some sulfur compounds have extrememly low odor thresholds, such as the
mercaptans, but those are unoxidized or reduced sulfur compounds, and I
would think that any sulfur-containing vapors that were generated near the
surface of the meteorite would be oxidized.
So, it is an interesting question, and I am curious to learn of other
people's thoughts on the subject. Thanks for the information.
Mark
Mark Grossman
Briarcliff Manor, NY
----- Original Message -----
From: "Piper R.W. Hollier" <pi...@xs4all.nl>
To: "Mark Grossman" <mar...@westnet.com>;
<meteorite-list@meteoritecentral.com>
Sent: Tuesday, November 23, 2010 3:03 PM
Subject: sulphurous smell of meteorites (was Temperature of meteorites)
Hello Mark and list,
Reports of some meteorites having a sulphurous smell have been of interest
to me for several years now. My thanks to Mark Grossman for the mention of
the Sears article (1974) and Ursula Marvin's speculations on the subject
(2007). I've not seen either reference yet and am curious about both.
While reports of sulphurous smells may have subsided, they have not by any
means ceased entirely. This list had a lively thread on this subject back
in the fall of 2007 soon after the Carancas fall. I'll recount a few
salient points of that discussion for those who are new to the list.
Visitors to the Carancas crater soon after the impact reported a sulfurous
odor, and 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 (e.g. in the moist lining of the lungs and
airways). One witness reported that meteoritic dust that had been stored
in a closed container after being collected near the crater gave a
sensation that she likened to the "stinging of a thousand little bees"
when the container was opened and the vapors inhaled.
Other relatively recent reports include:
- 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 March 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.
It is a well-know fact that sulfur is present in many types of meteorites.
Ordinary chondrites contain on average 2.1% sulfur, and carbonaceous
chondrites may contain as much as 6.6%. Sulfur in meteorites is normally
present entirely as troilite (FeS), but other sulfides are found in some
meteorites, and carbonaceous chondrites contain free sulfur, sulfates, and
possibly other sulfur compounds. (summarized from B. Mason, "Meteorites",
p. 160)
Less well-known is the fact that troilite dissociates at the rather low
temperature of 427 C (Sterling Webb found this figure somewhere during the
2007 discussion). This releases elemental sulfur that can in turn combine
with atmospheric oxygen to produce sulfur dioxide. The distinctive sharp
smell that a match gives off when being lit is due to the sulfur dioxide
formed when sulfur in the matchhead burns.
Thus it should not surprise us all that much that we continue to hear
reports of freshly-fallen meteorites having a sulfurous smell. It would be
a natural consequence of heating troilite in air.
Also interesting are reports that sulfurous odors may emanate from cut
meteorites long after the fall date. 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.
There would seem to be good reasons to believe that the laws of physics
and chemistry, and not just superstitious expectations, are behind these
"nose-witness" reports.
Best wishes to all,
Piper
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