Hodgkinsonite

Hodgkinsonite is named after H.H. Hodgkinson, discoverer of the mineral at Franklin, Sussex County, New Jersey, USA in 1913.

Franklin Mine, New Jersey has been the only source of facet-quality rough. The stones have been small, the colours are bright pink and lavender.

Hodgkinsonite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
General Information
Chemical Formula
Mn
2+
 
Zn
 
2
SiO
 
4
(OH)
 
2
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Photos of natural/un-cut material from mindat.org
Physical Properties of Hodgkinsonite
Mohs Hardness4.5 to 5
Arthur Thomas, Gemstones (2009)
Specific Gravity4.06 to 4.08
Michael O’Donoghue, Gems, Sixth Edition (2006)
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TenacityBrittle
Arthur Thomas, Gemstones (2009)
Cleavage QualityPerfect
Michael O’Donoghue, Gems, Sixth Edition (2006)
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FractureUneven
Arthur Thomas, Gemstones (2009)
Optical Properties of Hodgkinsonite
Refractive Index1.720 to 1.746
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Optical CharacterBiaxial/-
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Birefringence0.026
Michael O’Donoghue, Gems, Sixth Edition (2006)
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PleochroismLavender and pale purple for transparent pink stones.
Michael O’Donoghue, Gems, Sixth Edition (2006)
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DispersionModerate
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Brown, black, lavender, orange, pink, purple, violet
Arthur Thomas, Gemstones (2009)
TransparencyTransparent
Michael O’Donoghue, Gems, Sixth Edition (2006)
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LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (Long-Wave UV)Specimens may show a dull red fluorescence.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Hodgkinsonite
Crystal SystemMonoclinic
Michael O’Donoghue, Gems, Sixth Edition (2006)
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HabitStout prismatic crystals with steep pyramids or with dominating pyramids.
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Occurs as seams in massive willemite-franklinite granular ore in a metamorphosed stratiform zinc deposit.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Spectrographic Data
Calculated Spectra:
Click spectra for more information
Hodgkinsonite - Locality: Sterling Hill, New Jersey, USA
Further Information
Mineral information:Hodgkinsonite information at mindat.org
Significant Gem Localities
USA
 
  • New Jersey
    • Sussex Co.
      • Franklin Mining District
        • Franklin
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