MINERAL GEOCHEMISTRY AND ECONOMIC POTENTIAL OF THE SHAWANGUNK MINES, NEW YORK

The Shawangunk Mines located in Ulster, Sullivan, and Orange Counties, New York have a mining history starting in at least the 18th century and potentially earlier by Native Americans. These mines predominantly produced lead from galena with small amounts of zinc from sphalerite. The last mine to operate was the Shawangunk or Mamakating, which closed after World War I. The Shawangunk mines significance progressively decreased over time as a result of many causes such swings in the demand for particular minerals, changes in the economic climate, and finding other larger or higher-grade deposits. Equally as important, however, is that new technologies require different types of metals such as gallium, germanium, rare earth elements and others were not needed in the past but are critical today.

This study aims to re-examine the geochemistry of the sphalerite and galena found in the area. In particular, the silver concentrations found in the galena and the gallium, indium, and germanium found within the sphalerite deposits are of the greatest interest due to their uses in everyday life. These metals can be used in many different technologies, such as integrated circuits, optoelectronic devices, fiber optics, thin-film coatings, and metal alloys. In particular, these metals are vital towards technologies that are often tied with alternative energies. As technology advances a greater need for these metals will occur and it is necessary to re-examine historical districts like the Shawangunk. These metals that had no value in the past may be present in economic quantities within these historic deposits either in tailings piles, exploratory pits, or ore directly from the former mines. Wilbur et al., (1990) examined the geochemistry of sulfides from several of these mines but did not examine any of the metalloid elements that are critical metals. Since previous authors have classified this district as a “Mississippi Valley Type”, it is predicted using the model of Frenzel et al. (2016) that they should have higher levels of Ga and Ge. Preliminary qualitative handheld-XRF data shows elevated concentrations of arsenic and cadmium found in the sphalerite and in the galena. Samples will also be analyzed by bulk rock geochemistry to more accurately determine the concentrations of these critical metals.