BEMCO prospect (Charlotte Mine), Cranberry Lake, Byram Township, Sussex Co., New Jersey, USA

Ref.: Report of Investigation (ROI) #6885, Reconnaisance of Yttrium and Rare Earth Element Resources in Northern New Jersey, Williams, R.L. (1967), US Dept. of the Interior, Bureau of Mines; A Quest for New Jersey Minerals, Robert Speiser(1978):17. A uranium-RRE deposit in a semi-basic pegmatite, located near Cranberry Lake. Owned by the Byram Exploration & Mining Co. (BEMCO), Inc. Workings are comprised of shallow open cuts, a shaft and a raise with an inclined haulage way.

The BEMCO Mine uranium/rare earth deposit was discovered during the uranium rush of the 1950’s. With little governmental interference and no NIMBY’ism a short adit, sloped downward, guaranteeing flooding of the inner end, and a very short raise to the surface were driven into the hillside. On top of the hill a shallow trench was excavated on the outcrop. When I first saw this site almost 50 years ago I remember guys with geiger counters taking readings, making notes and hammering off samples. By the early 1960’s , after diamond drilling failed to indicate any down dip extention, activity ceased. Once, when I was there in the late 60’s or early 70’s I encountered 2 of the original owners/workers, puttering around. I can’t remember if they told me why. Whatever it was nothing came of it.

More recently the area became part of Allamuchy State Park. The uranium mine was rediscovered by the local population. In the changed social climate radiation hysteria took hold and the State backfilled the adit and placed steel bars over the raise.

The Bemco deposit is described by Vassiliou (1980). A thin, magnetite-rich band containing zircon and rare earth minerals occurs at the contact between a pegmatite dike and the enclosing sulphidic pyroxene gneiss. A variety of minerals have been attributed to the BEMCO mine but only magnetite and black zircon, enclosing cores of fergusonite and uranothorite, are common. Jaffe and Molinski (1962) described spenceite, now tritomite – Y, the second occurrence of this species.

There are a number of magnetite plus U/REE deposits scattered through the Reading Prong Highlands. The best known is the Doverite-bearing occurrence in the Scrub Oaks Mine. There is a widespread intimate relationship between these U/REE – bearing magnetite concentrations and pegmatites (Volkert, et al, 2005). U-Pb ages range between 990 and 940 MA.

Ref's: Jaffe, H. W., and Molinski, V. J., 1962, Spenceite, The Yttrium Analogue of Tritomite From Sussex County, New Jersey. The American Mineralogist, V. 47, P. 9 – 15.

Vassiliou, A. H., 1980, Uranium and Rare Earth Mineralization at the BEMCO Mine Near Cranberry Lake, New Jersey, in Manspeizer, W., Ed., field Studies of New Jersey Geology and Guide to Field Trips: 52nd Annual Meeting of the New York State Geological Association, p. 192 – 199.

Volkert, R.A., Zartman, R.E., and Moore, P.B., 2005, U – Pb Geochronology of Mesoproterozoic Postorogenic Rocks and Implications for Posty-Ottawan Magmatism and Metallogenesis, New Jersey Highlands and Contiguous Areas, USA. Precambrian Research, V. 139, pgs. 1 – 19. (and references therein)