[meteorite-list] sulphurous smell of meteorites (was Temperature of meteorites)

From: Piper R.W. Hollier <piper_at_meteoritecentral.com>
Date: Tue, 23 Nov 2010 21:03:44 +0100
Message-ID: <201011232005.oANK52Ki001863_at_smtp-vbr14.xs4all.nl>

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
Received on Tue 23 Nov 2010 03:03:44 PM PST