Friday, November 30, 2012



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.  

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

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.  

Noble, D.C., J.K. McCormack, E.H McKee, M.L. Silberman, and A.B. Wallace, A.B., 1988, Time of Mineralization in the Evolution of the McDermitt Caldera Complex, Nevada-Oregon, and the Relation of Middle Miocene Mineralization in the Northern Great Basin to Coeval Regional Basaltic Magmatic Activity: Economic Geology, v. 83