Hercynite, an iron aluminum oxide mineral of the spinel group, is a relatively rare mineral locally and has been little studied. It was first reported by Parker (1983), who noted that hercynite was found as dark reddish brown to black 1 cm crystals, associated with phlogopite and norbergite in the Franklin Quarry, formerly known as the Farber Quarry. It was verified as hercynite using a combination of X-ray diffraction and EDAX analysis. Hercynite is also found as the core of some chromian gahnite specimens from near the Sterling Hill orebody (Dunn and Frondel, 1990) and is discussed
above with gahnite. Hercynite has not been found in the orebodies; it is a mineral of the Franklin Marble. (Dunn, 1995)

 Location Found: Franklin and Ogdensburg
 Year Discovered: 1847
 Formula: Fe2+Al2O4
 Essential Elements: Aluminum, Iron, Oxygen
 All Elements in Formula: Aluminum, Iron, Oxygen
 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   Hercynite

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.581

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 27 No. 2 - Fall 1986, pg. 6Minerals of the Franklin Quarry, Philip P. Betancourt, Hercynite
View IssueV. 24 No. 2 - Fall 1983, pg. 9Mineral Notes Recent Discoveries, Hercynite
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