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Franklinphilite

A mixture of two or more distinct mineral species
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Colour:
Dark brown, black
Lustre:
Resinous, Waxy, Greasy
Hardness:
4
Specific Gravity:
2.6 - 2.8
Crystal System:
Triclinic
Name:
Named in 1992 by Pete J. Dunn, Donald R. Peacor, and Shu-Chun Su from "Franklin," its place of occurrence, and "phil" from the Greek for "love," in honor of all devotees or lovers of Franklin mineralogy.
A Mixture Of:
Lennilenapeite, Nelenite
According to IMA Proposal 25-B (2026), franklinphilite is a mixture of lennilenapeite and nelenite. Prior to the redefinition the formula was given as (K,Na)4(Mn2+,Mg,Zn)48(Si,Al)72(O,OH)216·6H2O.

Compare the chemically and stoichiometrically very similar coombsite.


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Unique IdentifiersHide

Mindat ID:
1599
Long-form identifier:
mindat:1:1:1599:4

IMA Classification of FranklinphiliteHide

IMA status:
Discredited
First published:
1992
Approval history:
IMA 25-B: Stilpnomelane group: composition range, franklinphilite and ekmanite discredited

franklinphilite is a mixture of lennilenapeite and nelenite ;
mineral is consequently discredited.

Classification of FranklinphiliteHide

Strunz-mindat (2026):
9..

9 : SILICATES (Germanates)
:
:
Dana 8th ed.:
74.1.1.3

74 : PHYLLOSILICATES Modulated Layers
1 : Modulated Layers with joined islands

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference for Standard
FkpIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
FkpWarr (2020)Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30

Physical Properties of FranklinphiliteHide

Lustre:
Resinous, Waxy, Greasy
Transparency:
Translucent, Opaque
Colour:
Dark brown, black
Streak:
Light brown
Hardness:
4 on Mohs scale
Tenacity:
Flexible
Cleavage:
Imperfect/Fair
(001)
Fracture:
Micaceous
Density:
2.6 - 2.8 g/cm3 (Measured)    2.66 g/cm3 (Calculated)

Optical Data of FranklinphiliteHide

Type:
Biaxial (-)
RI values:
nα = 1.545(5) nβ = 1.583(3) nγ = 1.583(3)
2V:
Measured: 10°
Birefringence:
0.038
Max. Birefringence:
δ = 0.038
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.

Surface Relief:
Moderate
Dispersion:
r > v distinct. Type description says dispersion was not detected.
Optical Extinction:
X ∧ (001) ≃ 6°.
Pleochroism:
Strong
Comments:
X = pale yellow, Y = Z = deep brown.

Crystallography of FranklinphiliteHide

Crystal System:
Triclinic
Cell Parameters:
a = 5.5214 Å, b = 9.5606 Å, c = 36.575 Å
Ratio:
a:b:c = 0.578 : 1 : 3.826
Unit Cell V:
0.00 ų (Calculated from Unit Cell)
Z:
3
Comment:
Z=3/8

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
High-? alteration and/or metamorphism
32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits

First Recorded Occurrence of FranklinphiliteHide

First Recorded Locality:
ⓘ Buckwheat pit, Franklin Mine, Franklin, Sussex County, New Jersey, USA
General Appearance of First Recorded Material:
Dark brown, radial aggregates of platy crystals.
Place of Conservation of First Recorded Material:
National Museum of Natural History, Washington, D.C., USA, 167390.
Associated Minerals at First Recorded Locality:
AegirineCalciteClino-suenoiteFriedeliteNelenite
Rhodonite

Synonyms of FranklinphiliteHide

Other Language Names for FranklinphiliteHide

Common AssociatesHide

Associations Based on Photo Data:
2 photos of Franklinphilite associated with NeleniteMn2+16As3+3Si12O36(OH)17
2 photos of Franklinphilite associated with Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
2 photos of Franklinphilite associated with CalciteCaCO3
1 photo of Franklinphilite associated with CaryopiliteMn2+3Si2O5(OH)4

Related Minerals - Strunz-mindat GroupingHide

9..'Ursilite'(Mg/Ca)4(UO2)4(Si2O5)5.5(OH)5 · 13H2OOrth.
9..'Oxy-uvite'
9..'Afanasyevaite'
9..'Tetranatrolite'
9..'Halloysite-7A'Mon. m : Bb
9..'Chlorophaeite'
9..'Sodicpedrizite'Mon. 2/m : B2/m
9..'Sodic-ferropedrizite'
9..'Oxy-rossmanite'
9..'Hiortdahlite I'Tric. 1 : P1

RadioactivityHide

Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 0.0000% 0 α, β, γ
Thorium (Th) 0.0000% 0 α, β, γ
Potassium (K) 1.8664% 579 β, γ

For comparison:

  • Banana: ~15 Bq per fruit
  • Granite: 1,000–3,000 Bq/kg
  • EU exemption limit: 10,000 Bq/kg

Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.

Interactive Simulator:

Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!

Activity: –

DistanceDose rateRisk
1 cm
10 cm
1 m

The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).

D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield

Fluorescence of FranklinphiliteHide

In UV light:
Not fluorescent in UV

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for FranklinphiliteHide

References for FranklinphiliteHide

Localities for FranklinphiliteHide

Showing 3 localities.

This 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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Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Switzerland
 
  • Grisons
    • Viamala Region
      • Rheinwald
        • Splügen
Roth et al. (2011) +1 other reference
UK
 
  • Wales
    • Gwynedd
      • Llanfair
www.museumwales.ac.uk (n.d.) +1 other reference
USA (FRL)
 
  • New Jersey
    • Sussex County
      • Franklin
        • Franklin Mine
Dunn et al. (1992) +1 other reference
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