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| TWINNED CINNABAR CRYSTALS IN GROUND MASS OF CALCITE AND QUARTZ. WIDTH OF SPECIMEN IS ~ 6.5 CM. THE CINNABAR CRYSTAL ON THE RIGHT IS ~ .7 CM AND DISPLAYS A SCARLET END SECTION FACING CAMERA. |
Mercury (quicksilver) is one of those interesting
minerals that I vividly remember from my college days in mineralogy and
chemistry. However, one must remember
that those days were long ago and generally before anyone thought too much
about mercury’s toxicity. But in those “olden”
days mercury was “fun” to play with since it is the only mineral metal that is
liquid at room temperature. I distinctly
remember “defacing” (in those days a federal crime I believe) copper pennies by
subjecting them to a bath in nitric acid.
We then smeared these reduced-size pennies with mercury and tried to
pass them off as dimes (when dimes were worth “more”). We also played games on the black lab tables
with moving liquid globs of mercury! In
mineralogy class, we loved to heat up ore and watch the mercury bubble up on
the surface. Have a time machine take us
back to the late 1990’s when a mercury thermometer broke on the floor in the
hallway of the science building. In a
few minutes the building was evacuated and the fire team arrived in space-like
hazmat suits (we soon replaced all of those mercury thermometers). In addition, when living in Wisconsin I
watched my dietary intake of fish caught in lakes contaminated by mercury. My
teeth have numerous amalgam fillings from 50 years ago. However, they are slowly breaking apart and
being replaced by quite expensive ceramic caps. As Bob Dylan crooned, The times they are a-changin’!
The other day, after an appointment with a dentist to
replace an amalgam filling, I was “thinking” about mercury. Did any of that metal really leach into my
system from over 50 years of having that mixture in my teeth? Did I eat too many walleye in past years? What about the chemistry labs, did I absorb
the liquid? I don’t seem to have any
symptoms of mercury poisoning so maybe I am “OK”. I am hoping that the odds for contracting mercury-related
problems are sort of like the odds in the recent Power Ball lottery ($550 million)
where a person was approximately 100 times more likely to be killed by a swarm
of killer bees than win the grand prize. I figure my chances are about the same
with the mercury.
After pondering these deep thoughts I decided to check
my collection since I knew that at least one specimen had some nice crystals of
cinnabar, the major ore of mercury. I
don’t know an awfully lot about cinnabar except that it is a scarlet color,
quite soft, and mines in Nevada had produced some nice crystals. I picked up this specimen at an auction and
it was unlabeled but I assumed Nevada (I learned that from Brian P). After
some detective work on the internet and in the library, I now am certain the specimen
is from Nevada, most likely from the Antelope Springs District in Pershing
County, and quite possibly the Red Bird Mine.
As far as I can tell, there are no operating mines
in the U.S where mercury is the primary objective; however, there may be
mercury produced as a byproduct of mining other metals. In past years Nevada was a (?the) major state
for the production of mercury and as a result parts of the state, especially in
western and central regions, are littered with abandoned mines. In the 1990’s the USGS begin a long-term
study examining the effects of the abandoned mines on the surrounding
ecosystems (Gray and others, 1999). They
noted: “Mercury is a heavy metal of environmental concern because highly
elevated concentrations are toxic to living organisms, and thus, the presence
of these abandoned mercury mines is a potential hazard to residents and
wildlife when drainage from the mines enters streams and rivers that are part
of local ecosystems…At the abandoned mercury mines in Nevada, the presence of
cinnabar remaining in ore and calcine piles (roasted ore), and any elemental
mercury around the mill and retort areas are environmental concerns. For
example, in all the districts studied, there is cinnabar visible in the area of
the open pit cuts and trenches, ore piles and tailings, as well as in the
calcine piles…Detrital cinnabar and cobbles containing cinnabar visible in
streams drainages below the mines indicate that mercury present at these sites
is eroding down gradient from the mines.”
That sounds like pretty messy stuff to me and I remain uncertain about cleanup
efforts, if any.
Mercury was mined in Nevada from about 1907
(discovered by then at Antelope Springs and with mining beginning in 1914)
until the early 1990’s. The District mines produced from veins in Triassic
limestone, dolomite, conglomerate, and shale (Gray and others, 1969). Evidently
these veins were emplaced during the Miocene as a result of extensional
magmatism (Noble and others, 1988). That
is, Miocene extensional tectonics involved the stretching of the earth’s crust
producing what we know today as the Basin and Range physiographic province.
Cinnabar, the major source of mercury, often is “massive”,
with poorly-formed crystals; however, there are exceptions and one of those
crystal localities is found in Nevada. Here
the individual crystals are large (for cinnabar), very soft (easily scratched
by a fingernail, 2-2.5 Mohs), and their scarlet color is often somewhat masked
on the surface and they seem to display a submetallic luster. However, underneath the surface the beautiful
scarlet color stands out with an adamantine luster. The Antelope Springs crystals are well known
among collectors as individuals are often twinned (penetration twins) with
six-sided crystals surrounding a top pyramid.
The twins are two “penetrated” individual crystals with a common C-axis
rotated 180 degrees from each other. At
Antelope Springs the ground mass is composed of calcite and quartz, some with
nice crystals.
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| PHOTOMICROGRAPH OF BROKEN CRYSTAL OF CINNABAR SHOWING FACE VISIBLE IN MACROPHOTO. |
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| PHOTMICTOGRAPH OF CRYSTAL OF CINNABAR WITH A NICE GEMMY CRYSTAL OF QUARTZ. |
As a point of interest (to me anyway) is that Meriwether
Lewis took along, as a medicine, substantial amount of mercury and mercurial
compounds to fight rampant outbreaks of venereal disease (and others) among the
boatmen. Some brought it along as a
pre-existing condition while other crew members picked it up along the way from
Native Americans who in turn had contracted it from British traders. The most famous of the mercury pills were the
Bilious Pills of Dr. Benjamin Rush.
These powerful pills, termed Rush’s Thunderbolts or Thunder Clappers
acted as a laxative and a body purger; they really cleaned out the digestive
system! The major ingredient of the
pills was mercury chloride. So, if the syphilis
didn’t get you, the gums bled and your teeth loosened and fell out. And if things were really bad the expedition
leaders had packed several urethral or penis syringes in order to inject
mercury solutions directly into the urethra.
Ouch! Those men were one tough breed. Today modern historians are able to
accurately locate many campsites of Lewis and Clark since the ground still
retains mercury---in elevated amounts!
In today’s hectic and uncertain world (the Fiscal
Cliff) I continue to remember Dylan’s
words:
Come
senators, congressmen
Please heed the call
Don't stand in the doorway
Don't block up the hall
Please heed the call
Don't stand in the doorway
Don't block up the hall
REFERENCES
CITED
Gray, J.E., M.G Adams, J.C. Crock, and P.M.
Theodorakos, 1999, Geochemical Data for Environmental Studies of Mercury Mines
in Nevada: U. S. Geological Survey Open-File Report 99-576.
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ReplyDeletehapcheta