Radioactive rare-earth deposit at Scrub Oaks mine, Morris County, New Jersey

Bulletin 1082- B
This report concerns work done on behalf of the U.S. Atomic Energy Commission and is published with the permission of the Commission
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Abstract

A deposit of rare-earth minerals in the Scrub Oaks iron mine, Morris County, N. J., was mapped and sampled in 1955. The rare-earth minerals are mainly in coarse-grained magnetite ore and in pegmatite adjacent to it. Discrete bodies of rare-earth-bearing magnetite ore apparently follow the plunge of the main magnetite ore body at the north end of the mine. Radioactivity of the ore containing rare earths is about 0.2 to 0.6 mllliroentgens per hour.

The principal minerals of the deposit are quartz, magnetite, hematite, albiteoligoclase, perthite and antiperthite. Xenotime and doverite aggregates and bastnaesite with intermixed leucoxene are the most abundant rare-earth minerals, and zircon, sphene, chevkinite, apatite, and monazite are of minor abundance in the ore. The rare-earth elements are partly differentiated into cerium-rich bastnaesite, chevkinite, and monazite, and yttrium-rich xenotime and doverite. Apatite, zircon, and sphene contain both cerium and yttrium group earths.

Eleven samples of radioactive ore and rock average 0.009 percent uranium, 0.062 percent thorium, 1.51 percent combined rare-earth oxides including yttrium oxide and 24.8 percent iron. Scatter diagrams of sample data show a direct correlation between equivalent uranium, uranium, thorium, and combined rare^ earth oxides. Both cerium- and yttrium-group earths are abundant in the rare-earth minerals.

Radioactive magnetite ore containing rare-earth minerals probably formed as a variant of the magnetite mineralization that produced the main iron ore of the Scrub Oaks deposit. The rare-earth minerals and the iron ore were deposited contemporaneously. Zircon crystals, probably deposited at the same time, have been determined by the Larsen method to be about 550 to 600 million years old (late Precambrian age).

Uranium, thorium, and rare-earth elements are potential byproducts of iron in the coarse-grained magnetite ore.

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Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Radioactive rare-earth deposit at Scrub Oaks mine, Morris County, New Jersey
Series title Bulletin
Series number 1082
Chapter B
DOI 10.3133/b1082B
Year Published 1959
Language English
Publisher U.S. Government Printing Office
Description Report: iv, 31 p.; Plate: 23.16 x 17.41 inches
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title Contributions to economic geology, 1958
First page 29
Last page 59
Country United States
State New Jersey
County Morris County
Other Geospatial Scrub Oaks mine