Thortveitite, a scandium silicate mineral, is a very rare mineral at Sterling Hill and has not been found at Franklin. It was found, in 20-micron crystals, as inclusions within a chromian zincian hercynite (with Fe > Zn) which is rimmed by chromian ferroan gahnite (with Zn > Fe) (Dunn and Frondel, 1990). This thortveitite, like those from many other occurrences, has minor Y substituting for Sc. Microprobe analysis gave Sc2O3 50, SiO2 45, Y2O3 4, total = 99 wt. %. Frondel (1970) provided data on the Sc content of the ores and calcium silicate units and reported maximum concentrations in andradite, pyroxenes, and amphiboles. It may be that this Sc is hosted, at least in part, as thortveitite inclusions. The gahnite/hercynite crystals which serve as a matrix for thortveitite are from the corundum/margarite assemblage in the Franklin Marble near the Sterling Hill orebody and are discussed under corundum and margarite. (Dunn, 1995)

 Location Found: Ogdensburg
 Year Discovered: 1911
 Formula: (Sc,Y)2Si2O7
 Essential Elements: Oxygen, Scandium, Silicon
 All Elements in Formula: Oxygen, Scandium, Silicon, Yttrium
 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   Thortveitite

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.421

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 32, No. 1 - Spring 1991, pg. 9An Uncommon Margarite/Corundum Assemblage From Sterling Hill, New Jersey, Pete J. Dunn, Clifford Frondel, Thortveitite (small description)
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