Tuesday, August 9, 2011
Panning for Gold, Carrollite, and Maybe Vesuvianite in Carroll County, MD
What you're looking at above are grains of sand, tiny ones, photographed at 40x. Searching primarily for gold, I panned them from a little stream passing near one of the sites in Carroll County Maryland in what is known as the Sykesville formation. It once produced copper and iron as well as sulfides rich in cobalt. From left to right are what appear be gold in quartz, garnet and carrollite. If not carrollite, the silvery gray piece at right is probably a closely related member of the linnaeite family of minerals, which includes carrollite, siegenite, and linnaeite itself.
Aware of but a single specimen bearing native gold to ever have been collected in this area, I figured that panning for it nearby could be my best approach; likewise for finding carrollite, the cobalt bearing species that derived its name from Carroll County after first being discovered there in the 1800's. Carrollite, like its close cousins siegenite and linnaeite (the species), is known to be a rare and very special find on the accessible dumps remaining in Carroll County.
However miniscule the quantity, if gold really is the source of yellow on that sub-millimeter grain of quartz, chalk it up to Lady Luck. No further such evidence of the yellow metal caught my attention amidst the thousands of particles to end up beneath my scope. Specks that appeared to be cobalt sulfide minerals, though not always easy to identify, were more numerous. I suspect many of these succumbed amidst endless grains of magnetite that were later separated with a magnet from the more interesting material.
Along with all the quartz grains that managed to survive were a few garnet grains. Garnet is likely to find its way into just about any stream in Maryland's Piedmont and is easy to identify. A particularly gemmy pale green and nearly transparent speck that was probably gahnite got away as I tried to separate it from thousands of surrounding particles with the thin sticky pin from the cap of a small tube of G-S Hypo Cement. Other attention grabbing particles were more challenging to identify. An example would be the brownish cube shown above at left. By sheer coincidence, and on an unrelated assignment the same day, I found myself photographing and became struck by how closely itvisually resembled the vesuvianite thumbnail from Coahuila, Mexico that's pictured at right. Interestingly, vesuvianite, albeit of different habit, is known to occur in at least one locality within the Sykesville formation. The specimen shown at left, which is in my personal collection is from the Fanny Frost Quarry, a few miles south across the line in Howard County.
I'm sure my friend Ev Smith, who introduced me to panning, would have successfully isolated a lot more interesting material using tools and equipment better suited for the task. I've recently been in touch with Ev and hope to tag along with him on an excursion in the coming weeks. Hopefully such an experience will render me more proficient not only at panning, but also at better mastering the art---or science---of separating the most interesting grains of sand from the myriad that are less so under the scope.