Franklin-Sterling Hill Mining District

Region East, Northeast
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Buffered point around the deposits.
Identified resources Historical production of cadmium, iron, and zinc.
Production The Sterling Hill mine began operating around 1739 and produced more than 11 million tons of Zn over its 247-year lifespan. The Scrub Oaks mine, which contained magnetite (Fe) and apatite (REE) ores formed by pegmatitic overprinting of volcanogenic seafloor deposits, produced intermittently until 1905; final closure in 1966 with an estimated total production of 7 million tons of iron ore.
Status Past mining. The Sterling Hill mine is currently a museum on the National Register of Historic Places listings in Sussex County, New Jersey.
Estimated resources Unknown.
Geologic maps Drake and others (1996), scale 1:100,000; Volkert and Monteverde (2013), scale 1:24,000.
Geophysical data Inadequate Rank 3 aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Proterozoic Franklin Marble in the Reading Prong Highlands. Rocks were metamorphosed to granulite grade during the Mesoproterozoic Ottawan orogeny (~1045 to 1024 Ma).
Deposits Sterling Hill mine (MRDS dep_id: 10198715), Franklin mine (MRDS dep_id: 10073174), Scrub Oaks mine (MRDS dep_id: 10021748; USMIN Site ID: NJ00006).
Evidence from mineral occurrences MRDS; USMIN.
Geochemical evidence Major zinc minerals (zincite, franklinite, and willemite) are oxides, not sulfides.
Geophysical evidence No anomaly.
Evidence from other sources See Volkert and others (2010).
Comments Known past producer but limited spatial extent. Benefit of geophysical surveys not known. Ore is hosted in a perthite-oligoclase granite. Drilling and analyses were performed in conjunction with USBM research (Williams, 1967). The Sterling Hill and Franklin zinc deposits are Basin brine mineral system, MVT-type deposits that were highly deformed and metamorphosed to granulite grade.
Cover thickness and description Cover less than 100 m?
Authors Anjana K. Shah, Bernard E. Hubbard, Nora K. Foley.
New data needs Detailed mapping of deposits, geophysics.
Geologic mapping and modeling needs 1:24,000 scale mapping of area around deposits.
Geophysical survey and modeling needs High resolution aeromagnetic and aeroradiometric coverage.
Digital elevation data needs Lidar complete.