Those in regional mineralogical circles know that the internationally cherished bright silvery cobalt bearing sulfide carrollite is eponymous with Carroll County Maryland. Carrollite, best known for magnificent cubo-octahedral crystals from Democractic Republic of Congo, is the only mineral species of the more than 5,000 that are known for which Maryland is the type locality. A 2009 Mineral Bliss post explains the interesting mineralogy relating to the "carrollite" as it occurs in Carroll County.
The specific type locality for carrollite in Carroll County was known as the Patapsco Mine(s), an operation that actually consisted of two mines: the Orchard Mine and the Wildeson Mine. Mining commenced in 1850 at the Wildeson Mine and in 1851 at the Orchard Mine. Both sites were mined for copper and by the 1870's iron.
A costly attempt to exploit a 1852 discovery of a vein rich in cobalt ore led the identification and subsequent publication of carrollite. It also led to the financial failure of the mines in 1854. Thereafter mining resumed for copper through leases and different ownership.
Soon after the discovery of carrollite, specimens bearing similar cobalt sulfides turned up elsewhere in southeastern Carroll County's Sykesville Mining District at the Mineral Hill Mine and the Springfield Mine. These occurrences were small enough that mining was never considered.
At least a few of the dumps, shafts, and pits of the Patapsco Mines, though overgrown and difficult to locate, were still accessible to a few cognoscenti in the late 1990's. By the turn of the millennium, remnants of the mining had been reclaimed or were considered to be lost. Collectors demonstrated minimal concern. The same kind of material the Patapsco Mines had yielded was easier to collect on the dumps of the Mineral Hill Mine.
A collector friend succeeded in locating what appeared to have once been a pit from one of the Patapsco Mines. On the ground nearby, we found lying on the ground several decent magnetite specimens with notable cleavage as well as rocks bearing significant malachite. Also present in a few rocks were very small amounts of epidote, pyrite, chalcopyrite, and bornite. We found no evidence of "carrollite."
After penetrating the surrounding dirt with a garden trowel, we found more that was too dirty to examine on site. The highlight of the day presented itself inside a rock that we broke open. Pictured at right, it appears to be chrysocolla, albeit of a deeper blue color than expected, some of which visually almost visually suggested azurite. The Natural History Society of Maryland's 1940 Minerals of Maryland publication by Ostrander and Price reported both species.
Having found significant magnetite but no hint of cobalt sulfides (carrollite), we believe that our filled in with soil apparent former pit may have been associated with the Orchard Mine. We base this conclusion on a Summer, 1998 article by Johnnie Johnsson in Matrix: A Journal of the History of Minerals (also our source for specific earlier given dates) that limits discussion of carrollite to the Wildesen Mine.
The same literature from 22 years ago describes other workings of the Patapsco Mines in a manner that begs for exploration. It mentions a "600 foot adit for extraction or drainage purposes." as well as "depressions in the area of the site near the river that could be from prospecting work, an adit, or remnants of the wheelhouse, crusher or furnace structures."
There may yet be more to seek.
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