Franklinite



Franklinite is an oxide mineral of the spinel group. It was first described in 1819, from samples from Franklin Furnace (now Franklin Borough) New Jersey. Charles Palache wrote: “The true character of the mineral was first determined by the French chemist Berthier, who named it franklinite ‘in order to remind us that that it was first found in a place to which the Americans have given the name of a great man.”

Though Franklin is the type locality, if you count Franklin and Sterling Hill, franklinite has been found in at least 30 localities worldwide. Nowhere else is franklinite so abundant, or found in large crystals (most commonly octahedral). Franklinite is a black non-fluorescent mineral, often associated with brilliantly fluorescent calcite and willemite, and also occurs with red or orange zincite, providing very colorful specimens. Franklinite is sometimes magnetic, but is a distinct mineral species from magnetite.


 Location Found: Franklin (Type Locality) and Ogdensburg
     
 
 Year Discovered: 1819
     
 Formula: Zn2+Fe23+O4
 Essential Elements: Iron, Oxygen, Zinc
 All Elements in Formula: Iron, Oxygen, Zinc
     
 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   Franklinite

     
 References:
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.566

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.56


The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 34, No. 2 - Fall 1993, pg. 13Recent Mineral Finds From The Sterling Mine Ogdensburg, New Jersey - Franklinite
View IssueV. 30, No, 2 - Fall 1989, pg. 19Research Reports, Franklinite-Gahnite Exsolution Intergrowths
View IssueV. 11, No. 2 - August 1970, pg. 10Additional Mineral Notes - Franklinite (small article)
View IssueV. 10, No. 1 - February 1969, pg. 6Mineral Notes - Franklinite
View IssueV. 9, No. 1 - February 1968, pg. 12The Exclusive Minerals of Franklin/Ogdensburg, N.J. (as of January 1968) by Frank Z. Edwards - Franklinite
View IssueV. 7, No. 2 - August 1966, pg. 8The Minerals of Sterling Hill 1962-65 by Frank Z. Edwards - Franklinite
View IssueV. 7, No. 1 - February 1966, pg. 7Franklinite (small article)
     
Images

     
Franklinite crystal in calcite matrix, Sterling Hill Mine
Franklinite crystal (about 1 1/2 inches across) in calcite matrix, Sterling Hill Mine, Ogdensburg, NJ. From the collection of, and photo by JVF.


Franklinite crystal 1 7/8 inch with minor willemite and calcite from Sterling Hill, NJ.
Franklinite crystal 1 7/8 inch with minor willemite (red) and calcite (white) from Sterling Hill, NJ. From the collection of, and photo by Robert A. Boymistruk.


Franklinite crystals in calcite from Sterling Hill Mine
Franklinite crystals (black) in calcite (white) from Sterling Hill Mine, NJ. 4" x 2 1/2" x 2". From the collection of, and photo by Robert A. Boymistruk.







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