RECENT ZINC ORE DISCOVERIES IN THE BALMAT-EDWARDS DISTRICT, NORTHWEST ADIRONDACKS, NEW YORK STATE: A CASE HISTORY

Over an eighty-seven-year period, the near world-class Balmat, zinc mining district, located in northern New York State, has produced 43 million tons of 9.4% zinc ore (containing 4 million tons of zinc metal). During the last 12 years, five new ore bodies, each with a unique case history, were discovered in the district. Between 1908 and 2004, on average, an ore body was discovered every 3-4 years.

Zinc ore, hosted by metamorphosed and polydeformed, Middle-Proterozoic siliceous dolomitic marbles, occurs as either conformable to relict bedding within certain stratigraphic horizons, or within cross-cutting, ductile shear zones. These ore types were reclassified as "parent" and "daughter," respectively (deLorraine, 2001). This most-recent development in the evolution of the district-wide exploration model has provided the additional insights required to find new ore in a mature district.

Mining in the district is concentrated in four areas: the Balmat mines, comprised of three mining units, named after their shafts, Nos. 2, 3 and 4 (discovered in 1927, 1945, and 1965, respectively); Edwards mine (1908); Pierrepont mine (1979); and Hyatt mine (1915). Prior to the recent discoveries, twenty-six individual ore bodies occurred in “clusters” that make up each of the six mining units. On average, “clusters” contain between 5-10M tons, and are composed of 4 ore bodies. The West Branch and Taylor ore orebodies were added to the Hyatt cluster in 1993 and 1995, respectively, while in the Balmat mine, it appears (subject to delineation drilling) that the three most recent discoveries (New Fold [1997], Mahler [2000], and Northeast Fowler [2004]) may establish a fourth mining "cluster"—the Balmat No. 5 Mine.