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Ca9(Si3O9)2(OH)8 · 8H2O
Specific Gravity:
2.32 - 2.33
Crystal System:
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).

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Classification of JenniteHide


9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains

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 : Silicates not Containing Aluminum
5 : Silicates of Ca

Physical Properties of JenniteHide

Transparent, Translucent
3½ on Mohs scale
Distinct on {001}
2.32 - 2.33 g/cm3 (Measured)    2.34 g/cm3 (Calculated)

Optical Data of JenniteHide

Biaxial (-)
RI values:
nα = 1.548 - 1.552 nβ = 1.562 - 1.564 nγ = 1.570 - 1.571
Measured: 74° , Calculated: 72° to 74°
Max Birefringence:
δ = 0.022
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
r < v strong

Chemical Properties of JenniteHide

Ca9(Si3O9)2(OH)8 · 8H2O
IMA Formula:
Ca9(Si3O9)2(OH)6 · 8H2O
Common Impurities:

Crystallography of JenniteHide

Crystal System:
Cell Parameters:
a = 10.56 Å, b = 7.25 Å, c = 10.81 Å
α = 99.7°, β = 97.67°, γ = 110.07°
a:b:c = 1.457 : 1 : 1.491
Unit Cell V:
749.71 ų (Calculated from Unit Cell)
Blade shaped crystals, fibrous aggregates.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
10.5 (vvs)
6.46 (ms)
3.47 (ms)
3.04 (s)
2.92 (vs)
2.83 (s)
2.66 (s)

Type Occurrence of JenniteHide

Place of Conservation of Type Material:
Smithsonian Museum 119007
Geological Setting of Type Material:
Late stage mineral in skarn

Synonyms of JenniteHide

Other Language Names for JenniteHide


Relationship of Jennite to other SpeciesHide

Structurally related to group(s):
Tobermorite GroupTobermorite group compounds are well known in the cement industry.

Common AssociatesHide

Associated Minerals Based on Photo Data:
Ettringite2 photos of Jennite associated with Ettringite on
Chabazite-Ca2 photos of Jennite associated with Chabazite-Ca on
Tobermorite2 photos of Jennite associated with Tobermorite on
Poldervaartite1 photo of Jennite associated with Poldervaartite on
Bultfonteinite1 photo of Jennite associated with Bultfonteinite on
Merwinite1 photo of Jennite associated with Merwinite on
Calcite1 photo of Jennite associated with Calcite on
Scawtite1 photo of Jennite associated with Scawtite on
Willhendersonite1 photo of Jennite associated with Willhendersonite on

Related Minerals - Nickel-Strunz GroupingHide

9.DG.05BustamiteCaMn2+(Si2O6)Tric. 1 : P1
9.DG.05PectoliteNaCa2Si3O8(OH)Tric. 1 : P1
9.DG.05SeranditeNaMn2+2Si3O8(OH)Tric. 1 : P1
9.DG.05WollastoniteCaSiO3Tric. 1 : P1
9.DG.08Plombièrite[Ca4Si6O16(OH)2 · 2H2O]·(Ca·5H2O)Orth.
9.DG.10Clinotobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Mon.
9.DG.10RiversideiteCa5(HSi3O9)2 · 2H2OOrth.
9.DG.10Tobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Orth.
9.DG.25ParaumbiteK3Zr2H(Si3O9)2 · nH2OOrth.
9.DG.25UmbiteK2(Zr,Ti)Si3O9 · H2OOrth.
9.DG.30SørenseniteNa4SnBe2Si6O16(OH)4Mon. 2/m : B2/b
9.DG.35XonotliteCa6(Si6O17)(OH)2Mon. 2/m
9.DG.40HillebranditeCa2(SiO3)(OH)2Orth. mmm (2/m 2/m 2/m) : Cmcm
9.DG.45ZoriteNa8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2OOrth.
9.DG.45ChivruaiiteCa4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2OOrth. mmm (2/m 2/m 2/m) : Cmmm
9.DG.50Haineaultite(Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2OOrth. 2 2 2 : C2 2 2
9.DG.55EpididymiteNa2Be2Si6O15 · H2OOrth. mmm (2/m 2/m 2/m) : Pnma
9.DG.60EudidymiteNa2Be2Si6O15 · H2OMon. 2/m : B2/b
9.DG.65ElpiditeNa2ZrSi6O15 · 3H2OOrth.
9.DG.75SenkevichiteCsKNaCa2Ti[O|Si7O18(OH)]Tric. 1 : P1
9.DG.80FluorcanasiteK3Na3Ca5Si12O30F4 · H2OMon. m : Bm
9.DG.85MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2OTric.
9.DG.90FrankameniteK3Na3Ca5(Si12O30)(F,OH)4 · H2OTric.
9.DG.92Charoite(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 · ~3H2OMon. 2/m : P21/m
9.DG.97Eveslogite(Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14Mon. 2/m : P2/m

Related Minerals - Dana Grouping (8th Ed.)Hide,Ti)(Si2O7)O2Mon.,OH)2Mon. 2/m : P21/båvenite(Na,Ca)2(Mn2+,Fe2+)(Zr,Ti)(Si2O7)(O,OH,F)2Mon. 2/m : P21/böhleriteNaCa2(Zr,Nb)(Si2O7)(O,OH,F)2Mon. 2 : P21,Nb)4(Si2O7)(O,OH,F)2Mon.,Ca)2Ca4Zr(Mn,Ti,Fe)(Si2O7)2(F,O)4 Tric. 1 : P1,REE)Ti(Si2O7)2OF3Tric. 1 : P1,Ca)3(Mn2+,Fe2+)3(Ti,Zr,Nb)2(Si2O7)2O2(OH,F)2Mon. 2/m : P21/m,Mn)Nb2[O3|Si2O7] · 3.5H2OOrth.,Ca,H)2Nb2Si2O10(OH,F)2 · H2OOrth. · H2OOrth. · nH2OTet.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.5.1WollastoniteCaSiO3Tric. 1 : P1
14.5.4RankiniteCa3Si2O7Mon. 2/m : P21/b
14.5.11AfwilliteCa3(HSiO4)2 · 2H2OMon. m : Bb
14.5.12XonotliteCa6(Si6O17)(OH)2Mon. 2/m
14.5.14HillebranditeCa2(SiO3)(OH)2Orth. mmm (2/m 2/m 2/m) : Cmcm
14.5.15JaffeiteCa6(Si2O7)(OH)6Trig. 3 : P3
14.5.16SuoluniteCa2(H2Si2O7) · H2OOrth.
14.5.18OkeniteCa10Si18O46 · 18H2OTric. 1 : P1
14.5.19RiversideiteCa5(HSi3O9)2 · 2H2OOrth.
14.5.20TrabzoniteCa4(Si3O9)(OH)2Orth. mm2 : Ama2
14.5.21GyroliteNaCa16Si23AlO60(OH)8 · 14H2OTric.
14.5.22FoshallasiteCa3[Si2O7] · 3H2O(?)
14.5.23Tobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Orth.
14.5.24Clinotobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Mon.
14.5.25NekoiteCa3Si6O15·7H2OTric. 1 : P1
14.5.26Plombièrite[Ca4Si6O16(OH)2 · 2H2O]·(Ca·5H2O)Orth.

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.

References for JenniteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Carpenter, A.B., Chalmers, R.A., Gard, J.A., Speakman, K., and Taylor, Harry Francis West (1966): Jennite, a new mineral: American Mineralogist 51, 56-74.
Gard, J.A., Taylor, H.F.W., Cliff, G., and Lorimer, G.W. (1977): A reexamination of jennite. American Mineralogist 62, 365-368.
Bonaccorsi, E., Merlino, S., and Taylor, H.F.W. (2004): The crystal structure of jennite, Ca9Si6O18(OH)6·8H2O. Cement and Concrete Research 34(9), 1481-1488.

Internet Links for JenniteHide

Localities for JenniteHide

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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Auvergne-Rhône-Alpes
    • Puy-de-Dôme
      • Clermont-Ferrand
        • Ceyrat
XRD analysis (B. Devouard and E. Médard, Clermont-Ferrand)
  • Bavaria
    • Franconia
      • Maroldsweisach
Wittern: "Mineralfundorte in Deutschland", 2001
  • Rhineland-Palatinate
    • Eifel
      • Mayen
        • Ettringen
          • Bellerberg volcano
[Hentschel, G., Die Mineralien der Eifelvulkane, Weise (München), 1983] [Lapis, 15 (5), 9-36]
in the collection of Christof Schäfer
Galuskin, E.V., Krüger, B., Krüger, H., Blass, G., Widmer, R., Galuskina, I.O. (2016): Wernerkrauseite, CaFe3+2Mn4+O6 - the first non-stoichiometric post-spinel mineral, from Bellerberg volcano, Eifel, Germany. European Journal of Mineralogy, 28, 485-493
  • Negev
Gross, S. (1977): The Mineralogy of the Hatrurim Formation, Israel. Geological Survey of Israel, Bulletin no. 70, 80 pp.
  • Latium
    • Viterbo Province
      • Montalto di Castro
        • Pietra Massa Locality
Passaglia, E. & Turconi, B. (1982): Silicati ed altri minerali di Montalto di Castro - VT. Rivista Mineralogica Italiana, 4/1982, 97-110.
  • Umbria
    • Perugia Province
      • Spoleto
Stoppa F., Scordari F., Mesto E., Sharygin V.V. and Bortolozzi G. - Calcium-aluminium-silicate-hydrate "cement" phases and rare Ca-zeolite association at Colle Fabbri, Central Italy (2010). Centr.Eur.J.Geosci. 2 (2), pag. 175-187 .
  • Honshu Island
    • Chugoku Region
      • Hiroshima prefecture
        • Hiba-gun
Kusachi et al (1984) Koubutsu-Gakkai Kou'en-Youshi, 100.
      • Okayama Prefecture
        • Takahashi City
          • Bicchu-cho (Bitchu-cho)
            • Fuka
Mineralogical Journal Vol. 14 (1989), No. 7 pp 279-292; Henmi, C., & Kusachi, I. (1992). Clinotobermorite, Ca5Si6 (O, OH) 18· 5H2O, a new mineral from Fuka, Okayama Prefecture, Japan. Mineralogical Magazine, 56(3), 353-358.
  • Amman
Pitty, A. F., & Alexander, W. R. (2010). A natural analogue study of cement buffered, hyperalkaline groundwaters and their interaction with a repository host rock IV: an examination of the Khushaym Matruk (central Jordan) and Maqarin (northern Jordan) sites. NDA-RWMD Technical Report, NDA, Moors Row, UK.
  • Irbid
    • Maqarin area
Pitty, A. F., & Alexander, W. R. (2010). A natural analogue study of cement buffered, hyperalkaline groundwaters and their interaction with a repository host rock IV: an examination of the Khushaym Matruk (central Jordan) and Maqarin (northern Jordan) sites. NDA-RWMD Technical Report, NDA, Moors Row, UK.; Khoury, H. N., Salameh, E., & Abdul-Jaber, Q. (1985). Characteristics of an unusual highly alkaline water from the Maqarin area, northern Jordan. Journal of Hydrology, 81(1), 79-91.
  • Michoacan
    • Mun. de Zitacuaro
Bernard, J.H. and Hyrsl, J. (2004) Minerals and their Localities. (Granit, Prague)
  • Telemark
    • Porsgrunn
Neumann, H. (1985): Norges Mineraler. Norges geologiske Undersøkelse Skrifter 68, 278 pp.
  • Northern Caucasus Region
    • Kabardino-Balkarian Republic
      • Baksan Valley
        • Upper Chegem volcanic caldera (Verkhnechegemskaya caldera)
A. E. Zadov data
Galuskina, I.O., Krüger, B., Galuskin, E.V. ,Armbruster, T., Gazeev, V.M., Włodyka, R., Dulski, M. & Dzierżanowski, P. (2015): Fluorchegemite, Ca7(SiO4)3F2, a new mineral from the edgrewitebearing endoskarn zone of an altered xenolith in ignimbrites from Upper Chegem Caldera, Northern Caucasus, Kabardina-balkaria, Russia; Occurrence, crystal structure, and new data on the mineral assemblages. Canadian Mineralogist. 53, 325-344.
  • Urals Region
    • Middle Urals
      • Sverdlovskaya Oblast'
        • Asbest
Antonov A.A. [Антонов А.А.] (2003): Mineralogy of rodingites of the Bazhenovsk ultrabasic massif [Минералогия родингитов Баженовского гипербазитого массива]. Nauka, Sankt-Peterburg, 129 pp. (in Russian).
  • Prešov Region
    • Vranov nad Topľou Co.
Ďuďa,R., et al., 1981: Mineralógia severnej časti Slanských vrchov. Min.Slovaca, Monografia 2, 98s
South Africa
  • Northern Cape Province
    • Kalahari manganese field
      • Hotazel
Von Bezing, K. L. et al. (1991) The Kalahari manganese field: An Update, Mineralogical Record 22(4) 279-302;
  • Western Region
    • Kabarole District
Barker, D.S. and Nixon, P.H. (1989) High-Ca, low-alkali carbonatite volcanism at Fort Portal, Uganda. Contributions to Minralogy and Petrology.: 103: 166-177.
  • California
    • Riverside Co.
      • Crestmore
Carpenter, A.B., R.A. Chalmers, J.A. Gard, K. Speakman & H.F.W. Taylor (1966), Jennite, a new mineral: American Mineralogist: 51: 56-74; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 479.
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