GOLD FROM MARYLAND?-YEP

 

Here in the Wisconsin woods winter seemed to arrive suddenly in early November. We were in a nice fall weather pattern with moderating winds tumbling down the maple leaves while I tried to keep the piles from a heavy covering of the grass. Boats were still on the river targeting freshwater river sturgeons and catfish. The “smarter” residents of my small neighborhood were in short sleeves installing outside Christmas lights and decorations. Then one night I heard the wind whistle in and here came Old Man Winter with freezing temps and in a couple of weeks night temps below zero. Thanksgiving arrived with blustering cold winds and snow while my spouse, daughter and I washed pots and pans for three hours at the community dinner. Then additional white stuff arrived, and the snow blower was cranked up several times. The big post-Thanksgiving events were: 1) the full moon, AKA the Cold Moon, arriving on December 4 floating above the eastern River bluffs as it started its journey across the sky to the western bluffs; and 2) the appearance of the first ice fisherman on the backwaters—a sure sign that winter had “really” arrived. In fact, we seem to be in the middle of several polar vortices keeping the temps “chilly”! Today, the 16^th of December, we are in a warm spell---the first time in several weeks the daytime temp was above freezing. Four days ago, the temp dropped down to at least 10 below with wind chills in the minus 20s. Hard water is here and the ice fishers are scattered on most bays, many snug in their little houses compete with heaters and TVs (to watch the Packers play football).

But the autumnal change to the cold season is a good thing for old rockhounds—I can hibernate in the downstairs office and play with minerals without being concerned about much outside yard work.  And the first of December is a sure sign that the Tucson shows are but two months away. Last year I missed the shows due to “settling in”  at our new abode in Wisconsin. Not so this coming season as Tucson here we come!

I am not a big spender at mineral shows but am usually happy with my buys/treasures although a few stinkers appear now and then.  Remember, as Bob Jones coined the term, I am a frugal collector.  I purchase less expensive specimens that “make me happy.”  I am not collecting for exhibits, or even local mineral shows, but for specimens that I can study and learn from.  Being a life-long learner is a high priority in my life!  Life is too short to be anything but happy.

Happiness, true happiness, is an inner quality. It is a state of mind. If your mind is at peace, you are happy. If your mind is at peace, but you have nothing else, you can be happy.    Dada Vaswani   

Living in the Plains, Midwest, and West over the decades, I am not overly familiar with the geology of the Appalachian chain of mountains. Oh, I have driven through and camped several times, I can spout off the creating orogenic events, and the physiographic provinces, etc. but outside of a few famous collecting localities/mines I remain a novice learner when it comes to minerals.  That is one reason I enjoy the professional, but semi-hard core, journals like Mineralogical Record and Rocks and Minerals. I joined mineral clubs inMaryland, Washington D.C., and eastern Canada to get a “non-western U.S. perspective” on geology and minerals and now read several eastern mineral club newsletters that are available on the Web.  Life is interesting.

I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived. Thoreau.

In rumbling around my basement office/storage I came across one of Willard Wulff’s specimens, gold no less, that I purchased a decade or so ago for about $3 at an estate sale. Willard W. Wulff Sr. was a Charter Member of the Colorado Springs Mineralogical Society who collaborated with Lazard Cahn to start the club in 1936. The specimen is mounted on a pedicle in a smaller Perky Box with handwritten labels in Wulff's very distinctive printing style. He acquired the specimen in 1962. I have a substantial number of Wulff's micromounts, in excess of 100, including several more gold mounts.

The gold was collected from the Maryland Mine, one of a group of gold mines-- the Ford, Anderson, Watson, and Maryland--- clustered in the southern section of Montgomery County, Maryland, near the town of Potomac just northwest of the Beltway near the Great Falls of the Potomac. Today, the Maryland, Ford and Anderson are part of the Chesapeake & Ohio Canal National Historic Park. These mines, along with at least thirty other gold mines and placers found in and around Montgomery County, are situated in the northern tip of a gold-bearing belt that extends in a shallow arc across the Piedmont from northeastern Alabama through northern Georgia, west central South Carolina, central North Carolina, central Virginia, and into south central Maryland. Within this region many gold mines were discovered and operated, beginning in the late eighteenth century, including the included the famous Dahlonega District of Georgia (Nagy and Parker, 2013), site of the first gold rush in the U.S. (1828) that resulted in forced removal of Native Americans (Trail of Tears), and the establishment of the Dahlonega Mint to mint gold coins (D mint mark) from 1838-1861).  

 

 

Reverse of an 1843 gold half eagle struck at the Dahlonega Mint. Public Domain photo courtesy John Reich. Note small D variety mint mark.

 The country rocks in the Maryland Mine area are complex, to say the least, that are part of the Neoproterozoic (~750 Ma) to Cambrian (~550 Ma???)  (they really don’t know its exact age) Mather Gorge Formation (Wissahickon Schist during my classroom days) that formed as the Supercontinent Rodinia broke apart (creating the proto-Atlantic Ocean). Originally the rocks were deposited as clastic sedimentary rocks shed into emerging oceanic trenches but later were subjected to regional volcanism and metamorphism during the Taconic (roughly Ordovician ~450 Ma), Acadian (roughly Devonian ~400 Ma), and Alleghenian (toughly Permian ~290 Ma) Orogenies. Today the country rock seems a mixed-up mess of interlayered mica schist and metamorphosed graywacke cut by dikes, sills, and small irregular plugs of light-colored granite and, locally, of lamprophyre. I have always had a great deal of respect to the mapping geologists working in the Appalachians.

 

The Maryland Mine, and others in the area, exploited quartz veins covering an area of about .25 miles wide by 3 miles long and ranging from a few inches to 14 feet in thickness that are part. They may be part of the Mather Gorge Formation but were probably formed later when late-stage, silica-rich, hydrothermal waters invaded cracks and fissures in the country rock. The gold and sulfide solutions traveled along (Nagy and Parker, 2013).

 

 Gold on quartz matrix from Maryland Mine. Width FOV ~ 7 mm.

 The Maryland Mine has an interesting history. Although extraction started around 1867 and the mine officially closed in 1940 as WW II was looming, it seemed to never live up to its potential as stated by the promotors. In 80+ years the Mine underwent numerous owners and investors, but “unlimited riches” never seemed to evolve and soon a new owner took over with big dreams. From ~1940 to 1951 “locals” prospected, panned, and broke rocks looking for the gold lode. One ounce of gold was shipped in 1951. Interestingly local panners are still able to collect dust, and a few nuggets, in the area’s streams. However, the Mine, and its associated dumps and trenches, are part of a National Historic Park and any sort of collecting is prohibited.

 

REFERENCES CITED

Nagy,J. & F. J. Parker, 2013, The Maryland Mine: Maryland's last underground gold mine: Rocks and Minerals Vol. 88, No. 5

DESAUTELS MICROMOUNT SYMPOSIUM AND DESAUTELSITE

 

I am a member of the Baltimore Mineral Society and have attended most monthly meetings for the last five years. Now Baltimore is a far distance from either Wisconsin (current home) or Colorado (past home) and purchasing airline tickets every month would break my Social Security budget! However, since the “Covid Pandemic” the Society has met via Zoom and even today their meetings are a hybrid with both Zoom and in-person. At most meetings the Zoom attendees from about 7-10 states and a couple of international locations often “outnumber” the in-person event. I feel very much at home via Zoom and the group has very lively and participatory mineral discussions. In addition, I have presented ~4 Power Point programs and contributed several manuscripts to their Newsletter.  Interestingly, many of the members seem like “old friends” although I have not personally met any of them and most likely will never attend an in-person event (due to expenses).

Each year the Society sponsors the Desautels Micromount Symposium and is the home of the Micromounters Hall of Fame. The Hall honors those who have supported and promoted micromounting during their collecting career.  In the early years, the Society honored “modern awardees” and a few “old timer awardees.”  In 1981, the initial year, Paul Desautels was inducted along with “old timers” George Fiss (d. 1925) and George Rakestraw (d. 1904). In examining the Hall of Fame recipients I noted the names of Lazard Cahn, 1982, the Honorary President for Life of CSMS, Arthur Roe, 1993, a founding member of CSMS who studied under Cahn, Jim Hurlbut, 2011, from the Denver area and a force in the Rocky Mountain Federation, Shorty Withers, 1995, the Honorary Curator of Micromounts at the Denver Museum of Science, and Arnold Hampson, 2012, of Cortez who donated his micromount collection to the Colorado School of Mines. Two micromounters are inducted each year with the 2025 inductees being long time collector Ron Gibbs from Arizona and David Roe who has wandered around and collected in Devon, England, UK, for decades.

Paul Desautels (1920-1991), for whom the Symposium is named, held many professional positions in his career but perhaps is best known for his 25 years spent as Curator of Gems and Minerals in the Department of Mineral Sciences in the U.S. National Museum of Natural History, AKA Smithsonian Institution. And perhaps, he was “the most influential curator of the 20^th century”. Desautels was awarded the Carnegie Mineralogical Award for his mineralogical contributions, the Smithsonian Director’s Medal, and the Tucson Gem and Mineral Show created an annual award for “mineral collecting connoisseurship” named the Desautels Trophy. Above from Hall of Fame .

In 1979 Desautels was honored when a new carbonate mineral was collected from the Baltimore Mafic Complex (1.1-1.0 Ga) in a Pennsylvania aggregate quarry (Cedar Hill)  and was named desautelsite [Mg₆Mn₂(OH)₁₆[CO₃]-4H₂O]  (Dunn and others, 1979).  It is a rare, bright orange mineral associated with fractures and cracks in rocks called serpentinite. These exposed metamorphic rocks (layered ultramafic, mafic, and volcanic rocks) are composed of  magnesium silicates formed by hydration and metamorphism of mantle rocks along boundaries of tectonic plates.  Several other secondary magnesium minerals are usually associated with desautelsite, including artinite [Mg₂(CO₃)(OH)₂-3H₂O)], and hydromagnesite [(Mg₅(CO₃)₄(OH)₂-4H₂O] although desautelsite is the last mineral to form in the fractures.

 

Druse of orange desautelsite on matrix. Width FOV ~ 4 mm. 

Desautelsite is a very soft mineral (2 on Mohs) with translucent pseudo- hexagonal crystals forming an orange, druse-like, scaly crust.  Without a powerful microscope the individual crystals are exceedingly difficult to observe.

Desautelsite is an extremely complex mineral, especially to an old plugger like me. It is a member of the Hydrotalcite Supergroup defined by their “natural layered double hydroxides…characterized by layered lattices (metal hydroxide layers alternating with carbonate and/or sulfate anions).”  I have poured over the defining article by Mills and others (2012) and my meager knowledge of crystal chemistry is just not sufficing for an adequate understanding.

MinDat (accessed 30 November) described the Super Group Hydrotalcite as containing, among others, desautelsite [Mg₆Mn₂(OH)₁₆[CO₃]-4H₂O], pyroaurite [Mg₆Fe³⁺₂(OH)₁₆[CO₃]-4H₂O] the iron analogue (whose Xray powder pattern is indistinguishable from desautelsite), and their solid solution group members stichite [Mg₆Cr³⁺₂(OH)₁₆[CO₃] - 4H₂, and hydrotalcite [Mg₆Al₂CO₃(OH)_{16 -}(H₂O)₄]. And then throw in iowaite [Mg₆Fe³⁺₂(OH)₁₆Cl₂ - 4H₂O], described in an October 19 Post, and which may weather to pyroaurite, and readers can understand my confusion (Defeat is not the worst of failures. Not to have tried is the true failure: G.E. Woodberry).

Although the Type Locality of desautelsite is in Lancaster County, Pennsylvania, the mineral is best known from two sites in California, especially the Artinite Pit in San Benito County, an open cut of exposed serpentinized rocks.  Secondary minerals like desautelsite grow on the altered surfaces of the spaces between the breccia blocks.  Other than these localities in Pennsylvania and California there is one locality in Maryland, and three in Japan, where the mineral occurs with other ultramafic rocks.  So, it is a rare mineral.

 

Acicular crystals of artinite, Mg₂(CO₃)(OH)₂-3H₂O, a low temperature alteration product in serpentinized ultrabasic rocks, that is associated with desautelsite.

REFERENCES CITED

Dunn, P.J., Peacor, D.R., Palmer, T.D.,1979, Desautelsite, a new mineral of the pyroaurite group: American Mineralogist, Vol. 64, No. 1-2.

Mills, S. J., Christy, A. G., Génin, J.-M. R., Kameda, T., Colombo, F., 2012, Nomenclature of the hydrotalcite supergroup: natural layered double hydroxides: Mineralogical Magazine, Vol.76, No.5.