Uraninite, a uranium oxide mineral, was reported by Frondel (1970) from Sterling Hill. Only one crystal was known from the original occurrence. It was found as a lustrous black cube, approximately 12 mm on edge, surrounded by an alteration zone which included uranophane. The matrix is franklinite/willemite ore with franklinite crystals up to 35 mm. Pink calcite encrusts the ore and contains abundant sphalerite and curved red fluorite. Lead-isotope measurements gave an age of 955 (± 30) million years for the ore at Sterling Hill.
In 1989, a specimen of uraninite associated with green clinopyroxene altering to amphibole and fluorapatite was found on the Buckwheat Dump in Franklin. The uraninite, verified by use of X-ray diffraction techniques, was a 4 x 5 mm rectangular crystal with very high luster on broken surfaces.
Semiquantitative microprobe analysis found this uraninite to be highly thorian with U > Th > Ce. Other specimens, also with 4 mm crystals, but associated with pyroxene and feldspar, were found in the same year and place. Information concerning these occurrences was well summarized by Dean (1990). (Dunn, 1995)

 Location Found: Franklin and Ogdensburg
 Year Discovered: 1772
 Formula: UO2
 Essential Elements: Oxygen, Uranium
 All Elements in Formula: Oxygen, Uranium
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
 To find out more about this mineral at minDat's website, follow this link   Uraninite

Dunn, Pete J. (1995). Franklin and Sterling Hill New Jersey: the world's most magnificent mineral deposits. Franklin, NJ.: The Franklin-Ogdensburg Mineralogical Society. p.605

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.81

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 50, No. 1 - Spring 2009, pg. 7Uraninite from the Trotter Dump
View IssueV. 31, No. 2 - Fall 1990, pg. 7Those Rare Uraninites From Franklin and Sterling Hill, New Jersey
View IssueV. 7, No. 2 - August 1966, pg. 14The Minerals of Sterling Hill 1962-65 by Frank Z. Edwards - Uraninite (small article)
View IssueV. 7, No. 1 - February 1966, pg. 9Uraninite
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