Jennite
A valid IMA mineral species
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About Jennite
Formula:
Ca9(Si3O9)2(OH)8 · 8H2O
Colour:
White
Lustre:
Vitreous, Sub-Vitreous, Silky
Hardness:
3½
Specific Gravity:
2.32 - 2.33
Crystal System:
Triclinic
Name:
Named in 1966 by Alden B. Carpenter, Robert A. Chalmers, John Alan Gard, K. Speakman, and Harry Francis West Taylor in honor of U. S. A. Army Colonel Clarence Marvin Jenni [November 3, 1896 USA - November 1, 1973 Columbia, Missouri, USA], curator of the Geological Museum of the University of Missouri (1960-1967, but he remained somewhat active as a curator in retirement until his passing in 1973), Columbia, Missouri, USA, and who discovered the mineral.
The structure of Jennite is composed of wollastonite-type dreier single chains (i.e. single chains with a repeating unit of three (SiO4) tetrahedra), ribbons of edge-sharing (CaO6) octahedra, and additional (CaO6) octahedra on inversion centers (Bonaccorsi et al., 2004).
Unique Identifiers
Mindat ID:
2087
Long-form identifier:
mindat:1:1:2087:5
Similar Names
| Giniite | A valid IMA mineral species | Fe2+Fe43+(PO4)3(OH)5 · 2H2O |
| Janite | ||
| Johnite | A synonym of Turquoise | |
| Juanite | A valid IMA mineral species - grandfathered - questionable | Ca10Mg4Al2Si11O39 · 4H2O or near |
| Junoite | A valid IMA mineral species | Cu2Pb3Bi8(S,Se)16 |
| Juonniite | A valid IMA mineral species | CaMgSc(PO4)2(OH) · 4H2O |
IMA Classification of Jennite
Approved
IMA Formula:
Ca9(Si3O9)2(OH)6·8H2O
Approval year:
1965
First published:
1966
Classification of Jennite
9.DG.20
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
56.2.4.11
56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
2 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or >[4] coordination
56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
2 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or >[4] coordination
14.5.27
14 : Silicates not Containing Aluminum
5 : Silicates of Ca
14 : Silicates not Containing Aluminum
5 : Silicates of Ca
Mineral Symbols
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.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Jnn | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Jnn | Warr (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 Jennite
Vitreous, Sub-Vitreous, Silky
Transparency:
Transparent, Translucent
Colour:
White
Streak:
White
Hardness:
3½ on Mohs scale
Cleavage:
Distinct/Good
Distinct on {001}
Distinct on {001}
Density:
2.32 - 2.33 g/cm3 (Measured) 2.325 g/cm3 (Calculated)
Optical Data of Jennite
Type:
Biaxial (-)
RI values:
nα = 1.548 - 1.552 nβ = 1.562 - 1.564 nγ = 1.570 - 1.571
2V:
Measured: 74° , Calculated: 72° to 74°
Birefringence:
0.022
Max. Birefringence:
δ = 0.019 - 0.022
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:
Low (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 strong
Optical Extinction:
X ⊥ {001} cleavage; Y ∧ b = 35°-40°.
Pleochroism:
Non-pleochroic
Chemistry of Jennite
Mindat Formula:
Ca9(Si3O9)2(OH)8 · 8H2O
Element Weights:
Elements listed:
Common Impurities:
Ti,Al,Fe,Mn,Mg,Na,K,P
Crystallography of Jennite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 10.576(2) Å, b = 7.265(2) Å, c = 10.931(3) Å
α = 101.30(1)°, β = 96.98(1)°, γ = 109.65(1)°
α = 101.30(1)°, β = 96.98(1)°, γ = 109.65(1)°
Ratio:
a:b:c = 1.456 : 1 : 1.505
Unit Cell V:
759.50 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Blade shaped crystals, fibrous aggregates.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Display Options
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Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
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Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
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Labels
Console Off | On | Grey | Yellow
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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) |
|---|---|---|---|---|---|---|---|
| 0012177 | Jennite | Bonaccorsi E, Merlino S, Taylor H F W (2004) The crystal structure of jennite, Ca9Si6O18(OH)6*8H2O Cement and Concrete Research 34 1481-1488 | 2004 | Fuka, Japan | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.5 Å | (100) |
| 6.46 Å | (50) |
| 5.95 Å | (6) |
| 5.20 Å | (6) |
| 4.77 Å | (40) |
| 4.48 Å | (10) |
| 4.11 Å | (20) |
| 3.93 Å | (6) |
| 3.72 Å | (6) |
| 3.55 Å | (20) |
| 3.47 Å | (50) |
| 3.29 Å | (50) |
| 3.19 Å | (6) |
| 3.04 Å | (60) |
| 2.92 Å | (80) |
| 2.83 Å | (60) |
| 2.78 Å | (40) |
| 2.66 Å | (60) |
| 2.61 Å | (20) |
| 2.52 Å | (6) |
| 2.43 Å | (6) |
| 2.40 Å | (6) |
| 2.27 Å | (20) |
| 2.21 Å | (10) |
| 2.08 Å | (10) |
| 2.04 Å | (50) |
| 1.984 Å | (40) |
| 1.957 Å | (30) |
| 1.946 Å | (30) |
| 1.875 Å | (10) |
| 1.833 Å | (10) |
| 1.810 Å | (50) |
| 1.735 Å | (20) |
| 1.683 Å | (30) |
| 1.637 Å | (10) |
| 1.610 Å | (20) |
| 1.580 Å | (10) |
| 1.521 Å | (10) |
| 1.486 Å | (10) |
| 1.455 Å | (10) |
| 1.413 Å | (20) |
| 1.393 Å | (6) |
| 1.365 Å | (6) |
| 1.331 Å | (10) |
| 1.312 Å | (20) |
| 1.266 Å | (6) |
| 1.214 Å | (6) |
| 1.177 Å | (6) |
| 1.173 Å | (20) |
| 1.155 Å | (6) |
Comments:
ICDD 18-1206.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
Type Occurrence of Jennite
General Appearance of Type Material:
White fibrous vein filling, composed of small blade-shaped crystals or fibrous aggregates.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 119007
Geological Setting of Type Material:
Late stage mineral in skarn.
Associated Minerals at Type Locality:
Synonyms of Jennite
Other Language Names for Jennite
Relationship of Jennite to other Species
Structurally related to group(s):
| Tobermorite Group | Ca4+x(AlySi6-y)O15+2x-y · 5H2O |
Common Associates
Associations Based on Photo Data:
| 5 photos of Jennite associated with Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O |
| 3 photos of Jennite associated with Bultfonteinite | Ca2(HSiO4)F · H2O |
| 2 photos of Jennite associated with Chabazite-Ca | (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O |
| 2 photos of Jennite associated with Tobermorite | Ca5Si6O17 · 5H2O |
| 1 photo of Jennite associated with Merwinite | Ca3Mg(SiO4)2 |
| 1 photo of Jennite associated with Scottyite | BaCu2Si2O7 |
| 1 photo of Jennite associated with Phillipsite-Ca | Ca3(Si10Al6)O32 · 12H2O |
| 1 photo of Jennite associated with Calcite | CaCO3 |
| 1 photo of Jennite associated with Willhendersonite | KCa[Al3Si3O12] · 5H2O |
| 1 photo of Jennite associated with Scawtite | Ca7(Si3O9)2CO3 · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 9.DG. | Barrydawsonite-(Y) | Na1.5Y0.5CaSi3O8(OH) |
| 9.DG. | Paratobermorite | Ca5AlSi5O16(OH) · 5H2O |
| 9.DG. | Calcinaksite | KNaCa(Si4O10) · H2O |
| 9.DG. | Alvesite | NaKZrSi6O15 · 2H2O |
| 9.DG.02 | Steedeite | NaMn2[Si3BO9](OH)2 |
| 9.DG.02 | Nolzeite | NaMn2[Si3BO9](OH)2 · 2H2O |
| 9.DG.05 | Murakamiite | LiCa2Si3O8(OH) |
| 9.DG.05 | Serandite | NaMn2+2Si3O8(OH) |
| 9.DG.05 | Bustamite | CaMn2+(Si2O6) |
| 9.DG.05 | Pectolite | NaCa2Si3O8(OH) |
| 9.DG.05 | Tanohataite | LiMn2Si3O8(OH) |
| 9.DG.05 | Dalnegorskite | Ca5Mn2+(Si3O9)2 |
| 9.DG.05 | 'Wollastonite-1A' | CaSiO3 |
| 9.DG.05 | Wollastonite | Ca3(Si3O9) |
| 9.DG.05 | Ferrobustamite | CaFe2+(Si2O6) |
| 9.DG.05 | Schizolite | NaCaMnSi3O8(OH) |
| 9.DG.07 | Cascandite | CaScSi3O8(OH) |
| 9.DG.08 | Plombièrite | Ca5Si6O16(OH)2 · 7H2O |
| 9.DG.10 | Clinotobermorite | Ca5Si6O17 · 5H2O |
| 9.DG.10 | Riversideite | Ca5Si6O16(OH)2 · 2H2O |
| 9.DG.10 | Tobermorite | Ca5Si6O17 · 5H2O |
| 9.DG.12 | Jusite | Na2Ca15Al4Si16O54 · 17H2O |
| 9.DG.12 | Kenotobermorite | Ca4Si6O15(OH)2 · 5H2O |
| 9.DG.15 | Foshagite | Ca4(Si3O9)(OH)2 |
| 9.DG.20 | Kamenevite | K2TiSi3O9 · H2O |
| 9.DG.25 | Paraumbite | K3Zr2H(Si3O9)2 · nH2O |
| 9.DG.25 | Umbite | K2(Zr,Ti)Si3O9 · H2O |
| 9.DG.30 | Sørensenite | Na4SnBe2Si6O16(OH)4 |
| 9.DG.32 | Escheite | Ca2NaMnTi5[Si12O34]O2(OH)3 · 12H2O |
| 9.DG.35 | Xonotlite | Ca6(Si6O17)(OH)2 |
| 9.DG.40 | Hillebrandite | Ca2(SiO3)(OH)2 |
| 9.DG.45 | Zorite | Na8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2O |
| 9.DG.45 | Chivruaiite | Ca4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2O |
| 9.DG.50 | Haineaultite | (Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2O |
| 9.DG.55 | Epididymite | Na2Be2Si6O15 · H2O |
| 9.DG.60 | Eudidymite | Na2Be2Si6O15 · H2O |
| 9.DG.65 | Elpidite | Na2ZrSi6O15 · 3H2O |
| 9.DG.65 | Patynite | NaKCa4[Si9O23] |
| 9.DG.67 | Whelanite | Cu2+2Ca6[Si6O17(OH)](CO3)(OH)3 · 2H2O |
| 9.DG.70 | Enricofrancoite | KNaCaSi4O10 |
| 9.DG.70 | Yusupovite | Na2Zr(Si6O15) · 2.5H2O |
| 9.DG.70 | Litidionite | KNaCuSi4O10 |
| 9.DG.70 | Fenaksite | (K,Na)4(Fe,Mn)2(Si4O10)2(OH,F) |
| 9.DG.70 | Manaksite | KNaMnSi4O10 |
| 9.DG.75 | Senkevichite | CsKNaCa2TiO[Si7O18](OH) |
| 9.DG.75 | Tinaksite | K2Na(Ca,Mn2+)2TiO[Si7O18(OH)] |
| 9.DG.75 | Tokkoite | K2Ca4[Si7O18(OH)](OH,F) |
| 9.DG.80 | Fluorcanasite | K3Na3Ca5Si12O30F4 · H2O |
| 9.DG.80 | Canasite | K3Na3Ca5Si12O30(OH)4 |
| 9.DG.85 | Miserite | K1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O |
| 9.DG.90 | Frankamenite | K3Na3Ca5(Si12O30)(F,OH)4 · H2O |
| 9.DG.92 | Charoite | (K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O |
| 9.DG.95 | Yuksporite | K4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3 |
| 9.DG.97 | Eveslogite | (Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14 |
Fluorescence of Jennite
May fluoresce dull white shortwave, brighter in LED longwave.
Other Information
Thermal Behaviour:
Stable up to 70°C. From 70-90°C there is a sharp loss of water, totaling 7% of the initial weight.
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 Jennite
mindat.org URL:
https://www.mindat.org/min-2087.html
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References for Jennite
Reference List:
Carpenter, A. B., Chalmers, R. A., Gard, J. A., Speakman, K., Taylor, H. F. W. (1966) Jennite, a new mineral. American Mineralogist, 51 (1-2) 56-74
Gard, J. Alan, Taylor, Harry F. W., Cliff, Graham, Lorimer, Gordon W. (1977) A reexamination of jennite. American Mineralogist, 62 (3-4) 365-368
Localities for Jennite
Showing 28 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.
France | |
| XRD analysis (B. Devouard and E. Médard, Clermont-Ferrand) |
Germany | |
| Wittern (2001) +1 other reference |
| Lapis (5) +1 other reference |
| Galuskin et al. (2016) | |
| in the collection of Christof Schäfer | |
| Juroszek et al. (Ti 5 Fe) | |
| in the collection of Christof Schäfer | |
Israel | |
| Britvin et al. (2025) |
Italy | |
| Carlini et al. (2018) |
| Passaglia et al. (1982) |
| Wheeler et al. (1996) +1 other reference |
Japan | |
| Kusachi et al (1984) |
| Kusachi et al. (1989) +1 other reference |
Jordan | |
| Pitty et al. (2010) |
| Fleurance et al. (2013) |
| Galuskina et al. (2019) | |
| Khoury et al. (1985) +1 other reference |
Mexico | |
| Bernard et al. (2004) |
Middle East | |
| Gross (1977) | |
Norway | |
| Neumann (1985) |
Russia | |
| Galuskin et al. (2012) |
| A. E. Zadov data | |
| Galuskina et al. (2015) | |
| Антонов (2003) |
Slovakia | |
| Ďuďa et al. (1993) |
South Africa | |
| Pohl et al. (1991) |
Uganda | |
| Barker et al. (1989) |
USA (TL) | |
| Carpenter et al. (1966) +2 other references |
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Colle Fabbri, Spoleto, Perugia Province, Umbria, Italy