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Franklinite

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Sterling Mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex Co., New Jersey, USA
© Rob Lavinsky

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Formula:
Zn
2+
 
Fe
3+
2
O
 
4
System:IsometricColour:Black
Hardness:5½ - 6
Name:In honor of Benjamin Franklin, American statesman, and the locality of Franklin Furnace (now Franklin), New Jersey, which was named after him as well.


Spinel Group, Fe series

Classification of Franklinite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:4/B.02-60
Nickel-Strunz 10th (pending) edition ID:4.BB.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
B : With only medium-sized cations
Dana 8th edition ID:7.2.2.4

7 : MULTIPLE OXIDES
2 : AB2X4
Hey's CIM Ref.:7.5.10

7 : Oxides and Hydroxides
5 : Oxides of Zn, Cd and Hg
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Type Occurrence of Franklinite

Co-type Localities:Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
Trotter Mine (Lehigh Mine), Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
Sterling Mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex Co., New Jersey, USA
Year of Discovery:1819

Occurrences of Franklinite

Geological Setting:High temperature metamorphism of Fe, Zn, Mn-rich marine carbonates.

Physical Properties of Franklinite

Lustre:Metallic, Sub-Metallic
Diaphaneity (Transparency):Opaque
Colour:Black
Streak:Reddish brown to black
Hardness (Mohs):5½ - 6
Hardness (Vickers):VHN100=852 - 882 kg/mm2
Tenacity:Very brittle
Cleavage:None Observed
Parting:Fair parting on {111}
Fracture:Irregular/Uneven, Conchoidal
Density (measured):5.07 - 5.22 g/cm3
Density (calculated):5.163 g/cm3

Crystallography of Franklinite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fd3m (F41/d 3 2/m)
Cell Parameters:a = 8.45(2) Å
Unit Cell Volume:V 603.35 ų (Calculated from Unit Cell)
Z:8
Morphology:Otahedral crystals common; dodecahedral less common; cubic rare.
Twinning:Twinning on {111}

Optical Data of Franklinite

Type:Isotropic
RI values: n = 2.36(2)
Maximum Birefringence:δ = 0.000 - Isotropic minerals have no birefringence
Surface Relief:Very High
Type:Isotropic
Colour in reflected light:White to gray
Internal Reflections:Red

Chemical Properties of Franklinite

Formula:
Zn
2+
 
Fe
3+
2
O
 
4
Essential elements:Fe, O, Zn
All elements listed in formula:Fe, O, Zn
Analyical Data:
The variation in composition ratio of Zn:Fe results in a variable degree of magnetism.
Common Impurities:Mn,Ti,Al,M,Ca

Relationship of Franklinite to other Species

Related Minerals - Nickel-Strunz Grouping):
4.BB.05Brunogeierite
(Ge,Fe)Fe
 
2
O
 
4
4.BB.05Chromite
FeCr
 
2
O
 
4
4.BB.05Cochromite
(Co,Ni,Fe)(Cr,Al)
 
2
O
 
4
4.BB.05Coulsonite
FeV
 
2
O
 
4
4.BB.05Cuprospinel
Cu
2+
 
Fe
3+
2
O
 
4
4.BB.05Filipstadite
(Mn,Mg)
 
2
(Sb
 
.5
Fe
 
.5
)O
 
4
4.BB.05Gahnite
ZnAl
 
2
O
 
4
4.BB.05Galaxite
(Mn,Fe,Mg)(Al,Fe)
 
2
O
 
4
4.BB.05Hercynite
FeAl
 
2
O
 
4
4.BB.05Jacobsite
Mn
2+
 
Fe
3+
2
O
 
4
4.BB.05Manganochromite
(Mn,Fe)(Cr,V)
 
2
O
 
4
4.BB.05Magnesiocoulsonite
MgV
 
2
O
 
4
4.BB.05Magnesiochromite
MgCr
 
2
O
 
4
4.BB.05Magnesioferrite
MgFe
3+
2
O
 
4
4.BB.05Magnetite
Fe
2+
 
Fe
3+
2
O
 
4
4.BB.05Nichromite
(Ni,Co,Fe)(Cr,Fe,Al)
 
2
O
 
4
4.BB.05Qandilite
(Mg,Fe)
 
2
(Ti,Fe,Al)O
 
4
4.BB.05Spinel
MgAl
 
2
O
 
4
4.BB.05Trevorite
Ni
2+
 
Fe
3+
2
O
 
4
4.BB.05Ulvöspinel
Fe
 
2
TiO
 
4
4.BB.05Vuorelainenite
(Mn,Fe)(V,Cr)
 
2
O
 
4
4.BB.05Zincochromite
ZnCr
 
2
O
 
4
4.BB.05Tegengrenite
(Mg,Mn
2+
 
)
 
2
Sb
5+
0.5
(Mn
3+
 
,Si,Ti)
 
0.5
O
 
4
4.BB.10Hausmannite
MnMn
 
2
O
 
4
4.BB.10Hetaerolite
ZnMn
 
2
O
 
4
4.BB.10Hydrohetaerolite
ZnMn
 
2
O
 
4
·H
 
2
O
4.BB.10Iwakiite
Mn(Fe,Mn)
 
2
O
 
4
4.BB.15Maghemite
Fe
 
2
O
 
3
4.BB.15Titanomaghemite
Fe
3+
 
(Fe
3+
 
,Ti
4+
 
,Fe
2+
 
,[])
 
2
O
 
4
Related Minerals - Hey's Index Grouping:
7.5.1Zincite
(Zn,Mn
2+
 
,Fe
2+
 
)O
7.5.2Sweetite
Zn(OH)
 
2
7.5.3Ashoverite
Zn(OH)
 
2
7.5.4Wülfingite
Zn(OH)
 
2
7.5.5Gahnite
ZnAl
 
2
O
 
4
7.5.6Hetaerolite
ZnMn
 
2
O
 
4
7.5.7Hydrohetaerolite
ZnMn
 
2
O
 
4
·H
 
2
O
7.5.8Chalcophanite
(Zn,Fe,Mn)Mn
 
3
O
 
7
·3H
 
2
O
7.5.9Woodruffite
Zn(Mn
4+
 
,Mn
3+
 
)
 
5
O
 
10
·3½H
 
2
O
7.5.11Monteponite
CdO
7.5.12Montroydite
HgO

Other Names for Franklinite

Synonyms:
FranckliniteIsophaneMagnofrankliniteZinkoferrite
French names:
Ferrite de Zinc
German names:
FracklinitFranklinitZinkoferrit
Russian names:
Франклинит
Spanish names:
FracklinitaFranklinitaZinkoferrita

Other Information

Fluorescence in UV light:None.
Magnetism:Diamagnetic
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Franklinite

Reference List:American Mineralogist (1928): 13: 171-173.

Palache, C. (1935), The Minerals of Franklin and Sterling Hill, New Jersey, USGS Professional Paper 180: 45.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 698-707.

O'Neill, H.St.C. (1992) Temperature dependence of the cation distribution in zinc ferrite (ZnFe2O4) from powder XRD structural refinements. European Journal of Mineralogy: 4: 571-580.

Lucchesi, S., Russo, U., and Della Giusta, A. (1999) Cation distribution in natural Zn-spinels: franklinite. European Journal of Mineralogy: 11: 501-511.

Internet Links for Franklinite

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  • Raman and XRD data at RRUFF project
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  • Franklinite details from Handbook of Mineralogy (PDF)
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    Localities for Franklinite

    Hide Locality List
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Australia
     
    • South Australia
      • Eyre peninsula
        • Middleback Range
          • Iron Knob
    		www.crocoite.com (Steve Sorrell) and refs therein
    • Western Australia
      • Southern Cross Province
        • Mukinbudin
    		Lead, Zinc and Silver Deposits of Western Australia, 1999
    Germany
     
    • North Rhine-Westphalia
      • Sauerland
        • Iserlohn
          • Letmathe
    Kazakhstan
     
    • Atasu - Karazhal - Zhayrem area
    		Frank Dzubeck; Kayupova, M.M. (1965) Doklady of the Academy of Sciences U.S.S.R., Earth Science sections, 163, 97-100.
    Mexico
     
    • Chihuahua
      • Mun. de Aquiles Serdán
        • Santa Eulalia District
          • East Camp
    		Panczner (1987): 77-395.
    Republic of Macedonia
     
    • Pelagonian massif
    		Schweiz. mineral. petrogr. Mitt. (1994) 74, 321-328
    Russia
     
    • Eastern-Siberian Region
      • Transbaikalia (Zabaykalye)
        • Buriatia (Buryatia) Republic
          • Baikal area
            • Sludyanka (Slyudyanka)
          • Vitim Plateau
            • Biraya and Bya Rivers confluence area (Chara Basin)
    		P.M. Kartashov data
    • Northern Region
      • Murmanskaja Oblast'
        • Kola Peninsula
          • Khibiny Massif
            • Rasvumchorr Mt
    		P.M. Kartashov data
    www.koeln.netsurf.de/~w.steffens/lovo.htm
    South Africa
     
    • Mpumalanga Province
    		Minerals of South Africa
    Sweden
     
    • Dalarna
      • Hedemora
        • Garpenberg
    		Can. Min. (2001) 39 (6), 1675-1683
    • Värmland
      • Filipstad
    		Nysten, P., Holtstam, D. and Jonsson, E. (1999) The Långban minerals. In Långban - The mines,their minerals, geology and explorers (D. Holtstam and J. Langhof, eds.), Swedish Museum of Natural History and Raster Förlag, Stockholm & Chr. Weise Verlag, Munich, pp. 89-183.
    • Västmanland
      • Hällefors
        • Grythyttan
    		Kjell Gatedal
    USA
     
    • California
      • San Bernardino Co.
    		U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
        • Holcomb Valley
          • Fawnskin
    		Leavens & Patton: Axis 4 (1)13p (2008)
    • Colorado
      • Gilpin Co.
        • Central City District
    		Minerals of Colorado (1997) Eckels, E. B.
    • Nevada
      • Churchill Co.
        • Fairview District
          • Fairview Silver mine
    		NBMG Spec. Pub. 31 Minerals of Nevada
    • New Jersey
      • Bergen Co.
    		The Minerals of New York City & Its Environs, New York Mineralogical Club Bull., Vol. 3, No. 1, Manchester, J.G. (1931): 76.
      • Sussex Co.
        • Franklin Mining District
    		Palache(1935):47-48; Dunn(1995):Pt4:566-578.
    Palache(1935):47; Dunn(1995):Pt5:668.
    Palache(1935):47-48; Dunn(1995):Pt4:566-578.
    USGS Prof Paper 180(Palache, C.)(1930).
    Palache(1935):47; Dunn(1995):Pt4:498.
    Palache(1935):47.
          • Ogdensburg
            • Sterling Hill
    		Palache(1935):47.
    Common knowledge of occurrence.
    Palache(1935):47-48; Dunn(1995):Pt4:566-578.
    • New Mexico
      • Hidalgo Co.
        • Steins Pass District
    		Northrop, Minerals of New Mexico, 3rd rev. ed, 1996
    Mineral and/or Locality
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