Pearcite/Polybasite etc
5 messages in this thread
Hi Doug,
I've been sniffing as per your advice and must say that your advice plus my
nose (somewhat addled by 20 years on Marlboros) seem to work.
Acanthite (Argentite) gives a clear "rotten eggs" aroma when warmed on the
family waffle iron. No need to heat very much to get the message.
The fragments of Polybasite (may-be-Peaceite), well heated on the same
scientificic instrument, give a clear fresh (not cooked) garlic signal, without
overtones of rotten eggs. Although the results, as you say, are not conclusive,
I am very pleased that we have at least a tongue in cheek identification.
Careful study of the morphology of Pearceite and Polybasite under a mike (the
"Pearceite" has much less tendency to hexagonal edges than the Polybasite I
have) plus the bouquet, give grounds for a tongue in cheek declaration on the
Pearcite. I don't think many Tucson dealers do a lot of X-ray or density
measurement work on their flats of Pearceite.
While I was wagging my nose over the waffle iron, the "Pearceite" gently
fragmented (I forgot the gas was on "High"); there was absolutely no sign of
cleavage.
One other useful indicator: I ended up with what might be classified as a
"low-class tequila" hangover; trying to be too precise over the grade of
garlic, I think!
Regards,
Chris
Hi, Chris–
Whew, you like to live dangerously. I would never have forgotten to turn off
the heat at the first whiff of either "rotten eggs" or "garlic" – I hope you
were outdoors! I should have suggested very small samples; a few grains of
powder in a tube should have been enough (your remark about cleavage implies
you were using more than plenty).
The "rotten egg" smell is hydrogen sulfide – gram for gram just as deadly as
hydrogen cyanide – its only redeeming feature is that the smell will likely
drive you away before it kills you (but if you are too determined to stay, an
early symptom of poisoning is when your sense of smell cuts out…). The
"garlic" smell of arsenic may be a greater danger to me, since I like garlic!
I was sort of expecting the brimstone odor of sulfur dioxide rather than
hydrogen sulfide – didn't you smell any of the former?
–Doug
Doug,
I was a little naive about snorting sulfides, arsenates, etc. However, you last
reply is quite enough to bring me down to earth. My wife has taken it very
seriously, too, and the kitchen and waffle iron are off limits now for mineral
research. I used to crawwl into old adits with equal abandon until I came face
to face with miners who had been in rock fall accidents; they straightened out
my ideas very smartly.
I am not sure if I know the difference between brimstone and rotten egg smells
– can you recommend a safe snort to clearly identify the former?
The piece of "Pearceite" was about 1 cubic centimeter, so the snort was a "big
double". I have a friend who is doing his mineralogy thesis at the Miguel
Romero Museum, Tehuacan, Puebla, Mexico, and he has kindly offered to do an
analysis on my various, smelly sulfides, etc. I expect it will be about 14 days
before I get the results, so this topic will be on ice till then. However, this
and "Guanajuato Fluorescents" have proved very interesting for my geologist
friends at the mines, so I hope to have more interesting info when I get back
on this.
Regards,
Chris
Hi, Chris–
Sulfur dioxide is the odor of burning sulfur – unlike the "rotten egg" smell
of hydrogen sulfide, it produces a sensation like pool acid fumes in the nose
(and if you snort too much of it, in your lungs, I expect). It feels like a
poison gas ought to, as if your nose/throat/lung are being corroded (which they
are), and is as unwise to breathe as it feels, yet it is not nearly as
dangerous as the mild-seeming hydrogen sulfide. I am none too sure when to
expect sulfur dioxide or hydrogen sulfide in heating sulfide minerals; it
likely has much to do with how they are being heated, particularly whether it
is an oxidizing or reducing flame.
There are no "safe snorts" for smelling or tasting specimens, just varying
degrees of risk. Using the oxidizing part (outer, yellow or colorless) of a
blowpipe or torch flame seems less risky, as it would produce more sulfur
dioxide and less hydrogen sulfide, but I have no idea what other hazards it
might aggravate (mercury or lead vapors?). Strong ventilation, small specimen
quantities, and very light, brief sniffs are the only ways to limit the hazards
that I am sure of.
Many rockhounds will taste a suspected halite (salt) specimen, checking for the
salty taste. Since I know halite sometimes fluoresces bright orange-red
because of traces of manganese and _lead_, I tend to pass on this test even if
I am sure it is "harmless" halite.
–Doug
Chris-
H2S has a distinct "rotten egg" smell at relatively low dosages – < 20 ppm. If
you haven't smelled a rotten egg, just leave one out in the sunlight for a week
or so and then crack it open.
SO2, sulfur dioxide has a decidely sharp, irritating smell that will cause mild
mucosal swelling with accompanying sneezing or coughing at levels between 10
and maybe 100 ppm. It is often detected just as a match is ignited and first
flares up. Other than burning a match, lighting a small chunk of sulfur will
give you a "taste" of that articular compound.
Hope this descriptive text helps. I will get to work on uploading Material
Safety Data Sheets on these and other chemicals that we can encounter in our
hobby.
Michael