Hardystonite
A valid IMA mineral species - grandfathered
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About Hardystonite
Formula:
Ca2Zn[Si2O7]
Colour:
Light brownish white, pale greyish-white, whitish, very pale pinkish
Lustre:
Adamantine, Resinous, Dull
Hardness:
3 - 4
Specific Gravity:
3.396 - 3.443
Crystal System:
Tetragonal
Member of:
Name:
Named in 1899 by John E. Wolff after Hardyston Township, Sussex County, New Jersey, USA, locality of the Franklin orebody prior to incorporation of Franklin Borough in 1913. Hardyston Township surrounds the borough of Franklin today.
Type Locality:
In daylight, natural hardystonite is a very non-descript massive ashen white mineral distinguished from massive calcite by a lack of cleavage and a somewhat greasy luster. (Note: Many photographers over-expose images of hardystonite to accentuate the blue fluorescent brightness. Such photos are often called "eBay blue", because deceptive sellers wish to increase their sales, but disappointed buyers feel cheated because the actual fluorescence of hardystonite is fairly dim compared with associated species such as calcite, willemite, or esperite.)
Visit gemdat.org for gemological information about Hardystonite.
Visit gemdat.org for gemological information about Hardystonite.Unique Identifiers
Mindat ID:
1818
Long-form identifier:
mindat:1:1:1818:6
IMA Classification of Hardystonite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca2Zn2+Si2O7
First published:
1899
Classification of Hardystonite
9.BB.10
9 : SILICATES (Germanates)
B : Sorosilicates
B : Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
B : Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination
55.4.2.2
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
4 : Si2O7 Groups, Generally with No Additional Anions with cations in [8] and lower coordination
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
4 : Si2O7 Groups, Generally with No Additional Anions with cations in [8] and lower coordination
14.7.14
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 |
|---|---|---|
| Hdy | 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 Hardystonite
Adamantine, Resinous, Dull
Transparency:
Opaque
Colour:
Light brownish white, pale greyish-white, whitish, very pale pinkish
Streak:
White
Hardness:
3 - 4 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {001}; poor on {100} and {110}.
Good on {001}; poor on {100} and {110}.
Density:
3.396 - 3.443 g/cm3 (Measured) 3.42 g/cm3 (Calculated)
Optical Data of Hardystonite
Type:
Uniaxial (-)
RI values:
nω = 1.672 nε = 1.661
Birefringence:
0.009
Max. Birefringence:
δ = 0.011
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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Optical Extinction:
parallel
Pleochroism:
Non-pleochroic
Chemistry of Hardystonite
Mindat Formula:
Ca2Zn[Si2O7]
Element Weights:
Elements listed:
Common Impurities:
Al,Fe,Mn,Pb,Mg,Na
Crystallography of Hardystonite
Crystal System:
Tetragonal
Class (H-M):
42m - Scalenohedral
Space Group:
P421m
Cell Parameters:
a = 7.8287(16) Å, c = 5.0140(2) Å
Ratio:
a:c = 1 : 0.64
Unit Cell V:
307.30 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Large, rough crystals rare embedded in calcite or other matrix.
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) |
|---|---|---|---|---|---|---|---|
| 0010703 | Hardystonite | Louisnathan S J (1969) Refinement of the crystal structure of hardystonite, Ca2ZnSi2O7 Zeitschrift fur Kristallographie 130 427-437 |  | 1969 | Franklin, New Jersey, USA | 0 | 293 |
| 0002657 | Hardystonite | Bindi L, Bonazzi P, Rothlisberger F (2001) Hardystonite from Franklin Furnace: A natural modulated melilite American Mineralogist 86 747-751 | | 2001 | 0 | 293 | |
| 0018114 | Hardystonite | Warren B, Trautz O (1930) The Structure of Hardystonite Ca2 Zn Si2 O7 _cod_database_code 1011252 Zeitschrift fur Kristallographie 75 525-528 | 1930 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.533 Å | (1) |
| 5.016 Å | (15) |
| 4.222 Å | (7) |
| 3.911 Å | (1) |
| 3.716 Å | (38) |
| 3.500 Å | (4) |
| 3.086 Å | (63) |
| 2.871 Å | (100) |
| 2.767 Å | (13) |
| 2.508 Å | (8) |
| 2.475 Å | (36) |
| 2.423 Å | (13) |
| 2.388 Å | (7) |
| 2.314 Å | (8) |
| 2.284 Å | (5) |
| 2.2195 Å | (8) |
| 2.1711 Å | (1) |
| 2.1113 Å | (1) |
| 2.0389 Å | (14) |
| 1.9564 Å | (2) |
| 1.8985 Å | (6) |
| 1.8585 Å | (11) |
| 1.8447 Å | (5) |
| 1.8231 Å | (3) |
| 1.8079 Å | (1) |
| 1.7757 Å | (12) |
| 1.7620 Å | (38) |
| 1.7503 Å | (19) |
| 1.7316 Å | (9) |
| 1.623 Å | (1) |
| 1.6524 Å | (6) |
| 1.6413 Å | (3) |
| 1.6351 Å | (1) |
| 1.6006 Å | (5) |
| 1.5369 Å | (6) |
| 1.5343 Å | (5) |
| 1.5133 Å | (3) |
| 1.5082 Å | (5) |
| 1.4943 Å | (1) |
| 1.4671 Å | (8) |
| 1.4526 Å | (1) |
| 1.4346 Å | (7) |
| 1.4306 Å | (7) |
| 1.4073 Å | (3) |
| 1.3954 Å | (7) |
| 1.3850 Å | (7) |
| 1.3419 Å | (1) |
| 1.3333 Å | (4) |
| 1.3274 Å | (1) |
| 1.3243 Å | (1) |
| plus 25 lines to 1.0968 Å | (1) |
Comments:
ICDD 35-745, 35-745a
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 56 : Slag and smelter minerals (see also #51 and #55) |
Type Occurrence of Hardystonite
General Appearance of Type Material:
In banded ore, forming grains averaging about a millimeter in diameter.
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA, numbers 113594, 113608.
Geological Setting of Type Material:
Occurs in a metamorphosed zinc-manganese-iron silicate-oxide orebody.
Associated Minerals at Type Locality:
Other Language Names for Hardystonite
Relationship of Hardystonite to other Species
Member of:
Other Members of Melilite Group:
| Åkermanite | Ca2Mg[Si2O7] | Tet. 42m : P421m |
| Alumoåkermanite | (CaNa)Al[Si2O7] | Tet. 42m : P421m |
| Bennesherite | Ba2Fe2+[Si2O7] | Tet. 42m : P421m |
| 'Ferri-gehlenite' | Ca2Fe3+[AlSiO7] | |
| Ferroåkermanite | Ca2Fe[Si2O7] | Tet. 42m : P421m |
| Gehlenite | Ca2Al[AlSiO7] | Tet. 42m : P421m |
| Gugiaite | Ca2Be[Si2O7] | Tet. 42m : P42m |
| Hydroxylgugiaite | (Ca,◻)2(Si,Be)[(Be,Si)2O5.5(OH)1.5] | Tet. 42m : P421m |
| Okayamalite | Ca2B[BSiO7] | Tet. 42m : P421m |
Common Associates
Associations Based on Photo Data:
| 375 photos of Hardystonite associated with Willemite | Zn2SiO4 |
| 225 photos of Hardystonite associated with Franklinite | Zn2+Fe3+2O4 |
| 198 photos of Hardystonite associated with Calcite | CaCO3 |
| 191 photos of Hardystonite associated with Clinohedrite | CaZn(SiO4) · H2O |
| 96 photos of Hardystonite associated with Esperite | PbCa2Zn3(SiO4)3 |
| 39 photos of Hardystonite associated with Zincite | ZnO |
| 34 photos of Hardystonite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 19 photos of Hardystonite associated with Bustamite | CaMn2+(Si2O6) |
| 12 photos of Hardystonite associated with Diopside | CaMgSi2O6 |
| 11 photos of Hardystonite associated with Glaucochroite | CaMn2+(SiO4) |
Related Minerals - Strunz-mindat Grouping
| 9.BB.10 | Okayamalite | Ca2B[BSiO7] |
| 9.BB.10 | Jeffreyite | (Ca,Na)2(Be,Al)(Si2O7,HSi2O7) |
| 9.BB.10 | Alumoåkermanite | (CaNa)Al[Si2O7] |
| 9.BB.10 | Åkermanite | Ca2Mg[Si2O7] |
| 9.BB.10 | 'Ferri-gehlenite' | Ca2Fe3+[AlSiO7] |
| 9.BB.10 | Gehlenite | Ca2Al[AlSiO7] |
| 9.BB.10 | Ferroåkermanite | Ca2Fe[Si2O7] |
| 9.BB.10 | Cebollite | Ca5Al2(SiO4)3(OH)4 |
| 9.BB.10 | Hydroxylgugiaite | (Ca,◻)2(Si,Be)[(Be,Si)2O5.5(OH)1.5] |
| 9.BB.10 | Gugiaite | Ca2Be[Si2O7] |
| 9.BB.15 | Barylite | Be2Ba(Si2O7) |
| 9.BB.15 | 'Barylite-1O' | Be2Ba(Si2O7) |
| 9.BB.20 | Bennesherite | Ba2Fe2+[Si2O7] |
| 9.BB.20 | Andrémeyerite | BaFe2+2(Si2O7) |
Fluorescence of Hardystonite
Dull persistent purple to blue (SW UV); blue (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.
Industrial Uses:
None, but a common constituent of zinc rich slags from smelting processes.
Internet Links for Hardystonite
mindat.org URL:
https://www.mindat.org/min-1818.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Hardystonite
Reference List:
Wolff, J. E. (1900) Ueber Hardystonit, ein neues Kalk-Zinksilicat von Franklin Furnace, New Jersey. Zeitschrift für Krystallographie und Mineralogie, 32 (1-6). 1-3 doi:10.1524/zkri.1900.32.1.1
Wolff, John E.; Melczer, G. (1900) Hardystonit und Zink-Schefferit von Franklin Furnace, New Jersey. Zeitschrift für Kristallographie, 33 (1). 147-151 doi:10.1524/zkri.1900.33.1.147
Warren, Β.E.; Trautz, О.B. (1930) The Structure of Hardystonite Ca2ZnSi2O7. Zeitschrift für Kristallographie, 75 (1). 525-528 doi:10.1515/zkri-1930-0136
LOUSNATHAN, S. JOHN (1969) Refinement of the crystal structure of hardystonite, Ca2ZnSi2O7. Zeitschrift für Kristallographie, 130 (1-6). 427-437 doi:10.1524/zkri.1969.130.16.427
Sharma, Shiv K., Yoder, H.S., Matson, Dean W. (1988) Raman study of some melilites in crystalline and glassy states. Geochimica et Cosmochimica Acta, 52 (8). 1961-1967 doi:10.1016/0016-7037(88)90177-9
Shannon, Robert D., Iishi, Kazuaki, Allik, Toomas H., Liebertz, Josef, Rossman, George R. (1992) Dielectric constants of BaO and melilites and the oxide additivity rule. European Journal of Mineralogy, 4 (6) 1241-1250 doi:10.1127/ejm/4/6/1241
Kakitani, Satoru; Ishii, Hiroshi; Yamaguchi, Kazuhiro (1997) Synthesis of Solid Solutions Based on the Akermanite and/or Hardystonite Systems and Their Fluorescence Properties. Japanese Journal of Applied Physics, 36. 6793-6797 doi:10.1143/jjap.36.6793
Fredericci, C., Zanotto, E.D., Ziemath, E.C. (2000) Crystallization mechanism and properties of a blast furnace slag glass. Journal of Non-Crystalline Solids, 273 (1) 64-75 doi:10.1016/s0022-3093(00)00145-9
Bindi, Luca, Czank, Michael, Röthlisberger, François, Bonazzi, Paola (2001) Hardystonite from Franklin Furnace: A natural modulated melilite. American Mineralogist, 86 (5) 747-751 doi:10.2138/am-2001-5-615
Shannon, Robert D., Shannon, Ruth C., Medenbach, Olaf, Fischer, Reinhard X. (2002) Refractive Index and Dispersion of Fluorides and Oxides. Journal of Physical and Chemical Reference Data, 31 (4) 931-970 doi:10.1063/1.1497384
Gaft, Michael, Seigel, Harold, Panczer, Gerard, Reisfeld, Renata (2002) Laser-induced time-resolved luminescence spectroscopy of Pb2+ in minerals. European Journal of Mineralogy, 14 (6) 1041-1048 doi:10.1127/0935-1221/2002/0014-1041
Haussühl, S.; Liebertz, J. (2004) Elastic and thermoelastic properties of synthetic Ca2MgSi2O7 (åkermanite) and Ca2ZnSi2O7 (hardystonite). Physics and Chemistry of Minerals, 31 (8). 565-567 doi:10.1007/s00269-004-0416-9
Wu, Chengtie, Chang, Jiang, Zhai, Wanyin (2005) A novel hardystonite bioceramic: preparation and characteristics. Ceramics International, 31. 27-31 doi:10.1016/j.ceramint.2004.02.008
Dondi, Michele, Zanelli, Chiara, Ardit, Matteo, Cruciani, Giuseppe (2011) Co-Doped Hardystonite, Ca2(Zn,Co)Si2O7, a New Blue Ceramic Pigment. Journal of the American Ceramic Society, 94 (4). 1025-1030 doi:10.1111/j.1551-2916.2010.04203.x
Yao, Shanshan, Xue, Lihong, Yan, Youwei, Yan, Mifang (2011) Preparation and Luminescence Property of Red-Emitting Hardystonite Phosphors by Near-Ultraviolet Irradiation. Journal of the American Ceramic Society, 94 (5). 1477-1482 doi:10.1111/j.1551-2916.2010.04261.x
Becker, Petra, Libowitzky, Eugen, Bohatý, Ladislav, Liebertz, Josef, Rhee, Hanjo, Eichler, Hans-Joachim, Kaminskii, Alexander A. (2012) Temperature-dependent thermo-mechanical and Raman spectroscopy study of the SRS-active melilite-type crystal Ca2ZnSi2O7 (hardystonite) at its incommensurate-commensurate phase transition. physica status solidi (a), 209 (2). 327-334 doi:10.1002/pssa.201127415
Localities for Hardystonite
Showing 20 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.
Australia | |
| Parbhakar-Fox et al. (2019) |
Czech Republic | |
| Pauliš P. Mineralogické lokality ... |
France | |
| Vanaecker et al. (2014) |
| Vanaecker et al. (2014) |
Germany | |
| Bender et al. (1994) |
| Neschen (n.d.) |
| Elmar Lackner collection +1 other reference |
| Besteman | |
Mexico | |
| Espejel-Garcia et al. (2012, December) |
Namibia | |
| Ettler et al. (2009) |
Poland | |
| Cempa et al. (2024) |
| Puziewicz et al. (2007) +2 other references |
USA | |
| Verbeek et al. (2014) |
| Piatak et al. (2010) |
| Palache (1935) +1 other reference |
| King (n.d.) | |
| Christopher O'Neill | |
| King (n.d.) +1 other reference | |
| Weissman purchased specimen |
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Franklin Mine, Franklin, Sussex County, New Jersey, USA