Hodgkinsonite
A valid IMA mineral species - grandfathered
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About Hodgkinsonite
Formula:
Mn2+Zn2(SiO4)(OH)2
Colour:
Bright pink or red to reddish brown and orange, pale pink, rarely yellow; black from tarnishing or inclusions.
Hardness:
4½ - 5
Specific Gravity:
4.06 - 4.08
Crystal System:
Monoclinic
Name:
Named in 1913 by Charles Palache and Waldemar Theodore Schaller in recognition of Harold Howe Hodgkinson [June 2, 1886 Toronto, Ontario, Canada - October 10, 1947 New Rochelle, New York, USA], assistant Underground Superintendent of the Franklin Mine and the person who brought the mineral to the attention of Charles Palache. In later life, Hodgkinson rose in business to be president of the Hodge and Hammond Company, dealers of construction equipment in the Bronx, New York.
Visit gemdat.org for Unique Identifiers
Mindat ID:
1913
Long-form identifier:
mindat:1:1:1913:8
IMA Classification of Hodgkinsonite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Zn2+2Mn2+SiO4(OH)2
Classification of Hodgkinsonite
9.AE.20
9 : SILICATES (Germanates)
A : Nesosilicates
E : Nesosilicates with additional anions (O,OH,F,H2O); cations in tetrahedral [4] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
E : Nesosilicates with additional anions (O,OH,F,H2O); cations in tetrahedral [4] coordination
52.2.1.3
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
2 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [4] and >[4] coordination
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
2 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [4] and >[4] coordination
14.7.20
14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Hgk | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Hodgkinsonite
Transparency:
Transparent, Translucent
Colour:
Bright pink or red to reddish brown and orange, pale pink, rarely yellow; black from tarnishing or inclusions.
Hardness:
4½ - 5 on Mohs scale
Cleavage:
Perfect
{011}
{011}
Density:
4.06 - 4.08 g/cm3 (Measured) 4.07 g/cm3 (Calculated)
Optical Data of Hodgkinsonite
Type:
Biaxial (-)
RI values:
nα = 1.720 - 1.724 nβ = 1.741 - 1.742 nγ = 1.746
2V:
Measured: 50° to 60°
Max. Birefringence:
δ = 0.022 - 0.026
Based on recorded range of RI values above.
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. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
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. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r < v moderate
Pleochroism:
Weak
Comments:
In shades of lavender and pale purple.
Chemistry of Hodgkinsonite
Mindat Formula:
Mn2+Zn2(SiO4)(OH)2
Element Weights:
Common Impurities:
Fe,Mg,Ca
Crystallography of Hodgkinsonite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 11.761(2) Å, b = 5.316(2) Å, c = 8.171(2) Å
β = 95.25(8)°
β = 95.25(8)°
Ratio:
a:b:c = 2.212 : 1 : 1.537
Unit Cell V:
508.72 ų (Calculated from Unit Cell)
Z:
4
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0015595 | Hodgkinsonite | Solov'eva L P, Belov N V (1963) Crystal structure of hodgkinsonite Zn2Mn[SiO4](OH)2 Soviet Physics Doklady 8 867-870 | 1963 | Franklin, New Jersey | 0 | 293 | |
| 0010606 | Hodgkinsonite | Rentzeperis P J (1963) The crystal structure of hodgkinsonite Zn2Mn[(OH)2|SiO4] Zeitschrift fur Kristallographie 119 117-138 |  | 1963 | Franklin, New Jersey | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.864 Å | (100) |
| 2.957 Å | (90) |
| 1.547 Å | (85) |
| 2.567 Å | (65) |
| 1.412 Å | (65) |
| 2.115 Å | (60) |
| 1.594 Å | (60) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Hodgkinsonite
Co-Type Localities:
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, 89875, 89880, 89881; National Museum of Natural History, Washington, D.C., USA, 87231.
Associated Minerals at Type Locality:
Other Language Names for Hodgkinsonite
Common Associates
Associations Based on Photo Data:
| 39 photos of Hodgkinsonite associated with Willemite | Zn2SiO4 |
| 38 photos of Hodgkinsonite associated with Franklinite | Zn2+Fe3+2O4 |
| 37 photos of Hodgkinsonite associated with Zincite | ZnO |
| 34 photos of Hodgkinsonite associated with Hetaerolite | ZnMn2O4 |
| 14 photos of Hodgkinsonite associated with Chlorophoenicite | (Mn,Mg)3Zn2(AsO4)(OH,O)6 |
| 12 photos of Hodgkinsonite associated with Baryte | BaSO4 |
| 11 photos of Hodgkinsonite associated with Native Copper | Cu |
| 7 photos of Hodgkinsonite associated with Lennilenapeite | K4Mn2+48[Si64Al8]O164(OH)52 · nH2O |
| 6 photos of Hodgkinsonite associated with Fluorite | CaF2 |
| 6 photos of Hodgkinsonite associated with Calcite | CaCO3 |
Related Minerals - Strunz-mindat Grouping
| 9.AE.05 | Beryllite | Be3(SiO4)(OH)2 · H2O |
| 9.AE.10 | Euclase | BeAl(SiO4)(OH) |
| 9.AE.15 | Sverigeite | NaMnMgSnBe2(SiO4)3(OH) |
| 9.AE.25 | Gerstmannite | MnMgZn(SiO4)(OH)2 |
| 9.AE.30 | Clinohedrite | CaZn(SiO4) · H2O |
| 9.AE.35 | Stringhamite | CaCu(SiO4) · H2O |
| 9.AE.40 | Katoptrite | (Mn2+,Mg)13(Al,Fe3+)4Sb5+2(SiO4)2O20 |
| 9.AE.45 | Yeatmanite | Zn6Mn2+9Sb5+2(SiO4)4O12 |
| 9.AE.50 | Sphaerobertrandite | Be3(SiO4)(OH)2 |
Fluorescence of Hodgkinsonite
weak pinkish red in LW UV.
Other Information
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 Hodgkinsonite
mindat.org URL:
https://www.mindat.org/min-1913.html
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Please feel free to link to this page.
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References for Hodgkinsonite
Reference List:
Palache, C., Schaller, W. T. (1913) Hodgkinsonite, a new mineral from Franklin Furnace, New Jersey. Journal of the Washington Academy of Sciences, 3 (19) 474-478
Palache, C.; Schaller, W. T. (1914) Hodgkinsonit, ein neues Mineral von Franklin Furnace, N.J. Zeitschrift für Kristallographie, 53 (1-6). 529-532 doi:10.1524/zkri.1914.53.1.529
Roberts, W. M. B., Quodling, F. M. (1962) X-ray, optical, and morphological observations on hodgkinsonite from Franklin Furnace. Mineralogical Magazine and Journal of the Mineralogical Society, 33 (259) 343-346 doi:10.1180/minmag.1962.033.259.08
Localities for Hodgkinsonite
Showing 4 localities.
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
USA (TL) | |
| Palache et al. (1913) +3 other references |
| Palache (1935) |
| FOMS Millsite Committee (1986) | |
| Cook (1973) +2 other references |
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Franklin Mine, Franklin, Sussex County, New Jersey, USA