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Offretite

Formula:
KCaMgAl
 
5
Si
 
13
O
 
36
·16H
 
2
O or near
System:HexagonalHardness:4 - 4½


Zeolite Group.

A zeolite difficult to distinguish from Erionite.

NOTE: The zeolite mineral species epitaxially overgrown on lévyne in all cases is identified as erionite (Passaglia et al., 1998).

Classification of Offretite

IMA status:Approved
Strunz 8th edition ID:8/J.26-70
Nickel-Strunz 10th (pending) edition ID:9.GD.25

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
D : Chains of 6-membered rings – tabular zeolites
Dana 8th edition ID:77.1.2.4

77 : TECTOSILICATES Zeolites
1 : Zeolite group - True zeolites
Hey's CIM Ref.:16.10.23

16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis
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Type Occurrence of Offretite

Type Locality:Mont Semiol (Mont Semiouse; Mont Simiouse), Montbrison, Loire, Rhône-Alpes, France
Year of Discovery:1890

Physical Properties of Offretite

Hardness (Mohs):4 - 4½

Crystallography of Offretite

Crystal System:Hexagonal
Class (H-M):6 m2 - Ditrigonal Dipyramidal
Space Group:P6m2
Cell Parameters:a = 13.29Å, c = 7.58Å
Ratio:a:c = 1 : 0.57
Unit Cell Volume:V 1,159.44 ų (Calculated from Unit Cell)

Epitaxial Relationships of Offretite

Epitaxial Minerals:
Erionite

Optical Data of Offretite

Type:Uniaxial (-)
RI values: nω = 1.489 - 1.495 nε = 1.486 - 1.492
Maximum Birefringence:δ = 0.003

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate

Chemical Properties of Offretite

Formula:
KCaMgAl
 
5
Si
 
13
O
 
36
·16H
 
2
O or near
Essential elements:Al, Ca, H, K, Mg, O, Si
All elements listed in formula:Al, Ca, H, K, Mg, O, Si
Common Impurities:Mg

Relationship of Offretite to other Species

Related Minerals - Nickel-Strunz Grouping):
9.GD.05Gmelinite-Ca
(Ca,Na
 
2
)[Al
 
2
Si
 
4
O
 
12
] · 6H
 
2
O
9.GD.05Gmelinite-K
(K
 
2
,Na
 
2
,Ca)[Al
 
2
Si
 
4
O
 
12
] · 6H
 
2
O
9.GD.05Gmelinite-Na
(Na
 
2
,Ca)[Al
 
2
Si
 
4
O
 
12
] · 6H
 
2
O
9.GD.10Willhendersonite
KCa[Al
 
3
Si
 
3
O
 
12
] · 5H
 
2
O
9.GD.10Chabazite-Ca
(Ca,K
 
2
,Na
 
2
)
 
2
[Al
 
2
Si
 
4
O
 
12
]
 
2
· 12H
 
2
O
9.GD.10Chabazite-K
(K
 
2
,Ca,Na
 
2
,Sr,Mg)
 
2
[Al
 
2
Si
 
4
O
 
12
]
 
2
· 12H
 
2
O
9.GD.10Chabazite-Na
(Na
 
2
,K
 
2
,Ca,Sr,Mg)
 
2
[Al
 
2
Si
 
4
O
 
12
]
 
2
· 12H
 
2
O
9.GD.10Chabazite-Sr
Sr
 
2
[Al
 
2
Si
 
4
O
 
12
]
 
2
· 12H
 
2
O
9.GD.15Lévyne-Ca
(Ca,Na
 
2
,K
 
2
)[Al
 
2
Si
 
4
O
 
12
] · 6H
 
2
O
9.GD.15Lévyne-Na
(Na
 
2
,Ca,K
 
2
)[Al
 
2
Si
 
4
O
 
12
] · 6H
 
2
O
9.GD.20Bellbergite
(K,Ba,Sr)
 
2
Sr
 
2
Ca
 
2
(Ca,Na)
 
4
[Al
 
3
Si
 
3
O
 
12
]
 
6
· 30H
 
2
O
9.GD.20Erionite-Ca
(Ca,K
 
2
,Na
 
2
)
 
2
[Al
 
4
Si
 
14
O
 
36
] · 15H
 
2
O
9.GD.20Erionite-K
(K
 
2
,Ca,Na
 
2
)
 
2
[Al
 
4
Si
 
14
O
 
36
] · 15H
 
2
O
9.GD.20Erionite-Na
(Na
 
2
,K
 
2
,Ca)
 
2
[Al
 
4
Si
 
14
O
 
36
] · 15H
 
2
O
9.GD.25Wenkite
(Ba,K)
 
4
(Ca,Na)
 
6
[(SO
 
4
)
 
3
|(Si,Al)
 
20
O
 
39
(OH)
 
2
] · 0.5H
 
2
O
9.GD.30Faujasite-Ca
(Ca,Na
 
2
,Mg)
 
3.5
[Al
 
7
Si
 
17
O
 
48
] · 32H
 
2
O
9.GD.30Faujasite-Mg
(Mg,Na
 
2
,Ca)
 
3.5
[Al
 
7
Si
 
17
O
 
48
] · 32H
 
2
O
9.GD.30Faujasite-Na
(Na
 
2
,Ca,Mg)
 
3.5
[Al
 
7
Si
 
17
O
 
48
] · 32H
 
2
O
9.GD.35Maricopaite
Pb
 
7
Ca
 
2
(Si,Al)
 
48
O
 
100
·32H
 
2
O
9.GD.35Mordenite
(Na
 
2
,Ca,K
 
2
)Al
 
2
Si
 
10
O
 
24
·7H
 
2
O
9.GD.40Dachiardite-Ca
(Ca,Na
 
2
,K
 
2
)
 
5
Al
 
10
Si
 
38
O
 
96
·25H
 
2
O
9.GD.40Dachiardite-Na
(Na
 
2
,Ca,K
 
2
)
 
5
Al
 
10
Si
 
38
O
 
96
·25H
 
2
O
9.GD.45Epistilbite
CaAl
 
2
Si
 
6
O
 
16
·5H
 
2
O
9.GD.50Ferrierite-K
(K
 
2
,Na
 
2
,Mg,Ca)
 
3-5
Mg[Al
 
5-7
Si
 
27.5-31
O
 
72
]·18H
 
2
O
9.GD.50Ferrierite-Mg
(Mg,Na
 
2
,K
 
2
,Ca)
 
3-5
Mg[Al
 
5-7
Si
 
27.5-31
O
 
72
]·18H
 
2
O
9.GD.50Ferrierite-Na
(Na
 
2
,K
 
2
,Mg,Ca)
 
3-5
Mg[Al
 
5-7
Si
 
27.5-31
O
 
72
]·18H
 
2
O
9.GD.55Bikitaite
LiAlSi
 
2
O
 
6
·H
 
2
O
Related Minerals - Hey's Index Grouping:
16.10.1Bytownite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
16.10.2Lisetite
CaNa
 
2
Al
 
4
Si
 
4
O
 
16
16.10.4Thomsonite-Ca
NaCa
 
2
[Al
 
5
Si
 
5
O
 
20
] · 6H
 
2
O
16.10.5Gonnardite
Na
 
2
Ca[Al
 
2
Si
 
3
O
 
10
]
 
2
· 7H
 
2
O
16.10.6Mesolite
Na
 
2
Ca
 
2
[Al
 
2
Si
 
3
O
 
10
]
 
3
· 8H
 
2
O
16.10.7Faujasite
16.10.8Garronite
Na
 
2
Ca
 
5
Al
 
12
Si
 
20
O
 
64
·27H
 
2
O
16.10.9Boggsite
Ca
 
8
Na
 
3
(Si,Al)
 
96
O
 
192
·70H
 
2
O
16.10.10Herschelite
16.10.11Phillipsite
16.10.12Fedorite
KNa
 
4
Ca
 
4
[HSi
 
4
O
 
10
]
 
4
· 6H
 
2
O
16.10.13Willhendersonite
KCa[Al
 
3
Si
 
3
O
 
12
] · 5H
 
2
O
16.10.14Barrerite
(Na,K,Ca
 
0.5
)
 
2
[Al
 
2
Si
 
7
O
 
18
] · 7H
 
2
O
16.10.15Mordenite
(Na
 
2
,Ca,K
 
2
)Al
 
2
Si
 
10
O
 
24
·7H
 
2
O
16.10.16Reyerite
(Na,K)
 
2
Ca
 
14
(Si,Al)
 
24
O
 
58
(OH)
 
8
·6H
 
2
O
16.10.17Lévyne
16.10.18Clinoptilolite
16.10.19Heulandite
16.10.20Gobbinsite
Na
 
4
(Ca,Mg,K
 
2
)Al
 
6
Si
 
10
O
 
32
·12H
 
2
O
16.10.21Stilbite
16.10.22Dachiardite
(Na,K,Ca
 
0
·5)
 
4
(Al
 
4
Si
 
20
)O
 
48
·18H
 
2
O
16.10.24Perlialite
K
 
9
Na(Ca,Sr)[Al
 
2
Si
 
4
O
 
12
]
 
6
· 15H
 
2
O
16.10.25Erionite
16.10.26Paulingite
16.10.27Sodium Dachiardite
(Na
 
2
,Ca,K
 
2
)
 
4-5
Al
 
8
Si
 
40
O
 
96
·26H
 
2
O
16.10.28Mazzite-Mg
K
 
2
Mg
 
2
Ca
 
1.5
Al
 
9.5
Si
 
26.5
O
 
72
·28H
 
2
O or near
16.10.29Roggianite
Ca
 
2
Be(OH)
 
2
Al
 
2
Si
 
4
O
 
13
·2.5H
 
2
O

Other Names for Offretite

German names:
Offretit
Russian names:
Оффретит
Spanish names:
Offretita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Offretite

Reference List:Sheppard, R.A. and Gude, A.J. (1969) Chemical composition and physical properties of the related zeolites offretite and erionite. American Mineralogist: 54: 875-886.

Gualtieri, A., G. Artioli, E. Passaglia, S. Bigi, A. Viani, and J.C. Hanson (1998): Crystal structure-crystal chemistry relationships in the zeolites erionite and offretite. American Mineralogist: 83: 590-606.

Passaglia, E., G. Artioli, and A. Gualtieri (1998): Crystal chemistry of the zeolites erionite and offretite. American Mineralogist: 83: 577-589.

Internet Links for Offretite

Search Engines:
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  • Look for Offretite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Offretite in the Natural History Museum (London) online catalogue
  • Offrétite details from Handbook of Mineralogy (PDF)
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    Localities for Offretite

    The 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.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Australia
     
    • New South Wales
      • Brisbane Co.
        • Merriwa
    Min Rec (1988) 19:389-406
      • Buckland Co.
    England, B. M. (1996): Zeolites and associated minerals from Borambil, New South Wales, Australia. Austral. J. Mineral. 2, 11-20.
    England, B. M. (2002): Zeolites and associated minerals from the Krui Valley, Merriwa, New South Wales. Austral. J. Mineral. 8, 61-71.
    • Tasmania
      • Devonport district
    http://www.crocoite.com/locationbulletins/part1/zeolites.pdf
    http://www.crocoite.com/locationbulletins/part1/zeolites.pdf
      • Moina District (Middlesex District)
    Bottrill & Baker (in prep) Catalogue of minerals of Tasmania
    • Victoria
      • Flinders
    Tschernich, R. (1992): Zeolites of the World, p.49
    Min Rec 17:6 p377-379
      • Gippsland
        • Howitt Plains
        • Willow Grove
      • Jindivick
    Tschernich, R. (1992): Zeolites of the World, p.49
      • Phillip Island
      • Woodend
        • Tylden
    Canada
     
    • British Columbia
      • Coalmont
    Tschernich, R. (1992): Zeolites of the World, p.300,385
      • Kamloops Mining Division
        • Monte Hills
    Tschernich, R. (1992): Zeolites of the World, p.99, 385
        • Westwold
    Tschernich, R. (1992): Zeolites of the World, p.98, 385
    Costa Rica
     
    • Guanacaste Province
    Micro Probe Vol 7 No. 7 Spring 1993
    Tschernich, R. (1992): Zeolites of the World, p.101,301,323,362,386,415,494; Micro Probe Volume VII Number 7 Spring 1993
    • San José Province
      • Bajo Chacones
    Micro Probe Volume VII Number 7 Spring 1993
    Czech Republic
     
    • Bohemia (Böhmen; Boehmen)
      • Central Bohemia Region
        • Kladno
    Pauliš, P.: Nejzajímavější mineralogická naleziště Čech. Kutná Hora: Kuttna, 2000, s. 84-85.
      • Ústí Region
        • Ústí nad Labem (Aussig)
    Rychlý, R., Langrová, A., Had, J.: Chemicstry of cowlesite from Zezice, Bohemia. Scripta Fac. Sci. Nat. Univ. Masaryk. Brun, Geol., 1996, vol. 26, p. 43 - 44.
    France
     
    • Auvergne
      • Haute-Loire
        • Yssingeaux
          • Araules
    Pongiluppi D. (1976) Offretite, garronite and other zeolites from "Central Massif", France. Bull. SFMC, 99: 322-327
    • Rhône-Alpes
      • Ardèche
        • Plateau des Coirons
          • Villeneuve-de-Berg
            • Saint-Jean-le-Centenier
    E. Passaglia et al. , Bull. Minéral. , 1985, 108, pp. 719-724. see also : http://membres.lycos.fr/volcanogeol/prismation/sites_france.htm
      • Loire
        • Montbrison
    C.R.Acad.Sci.Paris,(1890) 111, 1002-1003
    Germany
     
    • Baden-Württemberg
      • Kaiserstuhl
        • Sasbach
    No reference listed
    • Bavaria
      • Franconia
        • Fichtelgebirge
          • Marktredwitz
            • Pechbrunn
    Weiss: "Mineralfundstellen, Deutschland West", 1990
        • Maroldsweisach
    Wittern: "Mineralfundorte in Deutschland", 2001
      • Upper Palatinate
        • Oberpfälzer Wald
          • Mitterteich
            • Wiesau
    Pöllmann, H., (1990): Mineralparagenesen im Nephelinbasanit von Triebendorf/ Opf., Der Aufschluss, Vol. 41(4), 219-226
    • Hesse
      • Gießen (Giessen)
        • Annerod
    S. Weiß: "Mineralfundstellen, Deutschland West", Weise (Munich), 1990
        • Großen-Buseck
    S. Weiß: "Mineralfundstellen, Deutschland West", Weise (Munich), 1990
      • Vogelsberg
        • Gedern
        • Herbstein
        • Hungen
          • Langd
          • Oberwiddersheim
        • Ortenberg
        • Schotten
          • Gonterskirchen
    S. Weiß: "Mineralfundstellen, Deutschland West", Weise (Munich), 1990
    • Rhineland-Palatinate
      • Eifel Mts
        • Hillesheim
          • Zilsdorf
    Hentschel, G., Neue Mineralfunde aus Mineralvorkommen der Eifel, Mainzer geowiss. Mitt., 87-90, 1982
        • Mayen
          • Ettringen
    Blass, G., Emmerich, F., Graf, HW., Schäfer, Ch., Tschörtner, J., (2006): Minerale der Eifelvulkane, Version 1.0, CD, published by authors
    Hungary
     
    • Nógrád Co.
      • Karancs-Medves Mts.
        • Somoskő
    Szakáll: 100 Hungarian Mineral Locality, 2004
    • Veszprém Co.
      • Tapolcai Basin
        • Bazsi
    Mineral Species of Hungary, 2005
    Italy
     
    • Lombardy
      • Brescia Province
        • Adamello-Brenta Natural Park
          • Adamello Massif
            • Mt. Foppa
    E. Passaglia and A. Tagliavini : "Chabazite-offretite epitaxial overgrowths in cornubianite from Passo Forcel Rosso, Adamello, Italy", European Journal of Mineralogy, 1994, Vol. 6, N° 3, pp. 397-405.
    • Veneto
      • Verona Province
        • Soave
    Boscardin, M., Checchi, A., Filippi, F., Guglielmino, S., Pegoraro, S., Pretto, G., Zattra, A. (1998): Offrétite del Veneto. Rivista Mineralogica Italiana, 22(1), 25-29. Passaglia, E., Tagliavini. A., Gutoni, R. (1996): Offrétite and other zeolites from Fittà (Verona, Italy). Neues Jahrbuch für Mineralogie, Monatshefte, 1996(9), 418-428.
      • Vicenza Province
        • Chiampo
          • East Lessini Mts.
            • Roccolo Pass
    Daleffe, A. & Boscardin, M. (2005): Offretite di Passo Roccolo tra Chiampo e S. Giovanni Ilarione (Lessini orientali). Studi e Ricerche - Associazione Amici del Museo - Museo Civico "G. Zannato" Montecchio Maggiore (Vicenza), 12, 57-59.
        • Montorso Vicentino
          • Case Nori
    - M.Boscardin, A.Checchi,F.Filippi,S.Guglielmino,S.Pegoraro, G.Pretto & A.Zattra (1998) -Offretite del Veneto- Rivista Mineralogica Italiana, 22, (1),25 - 29.
        • San Pietro Mussolino
    Studi e Ricerche - Associazione Amici del Museo - Museo Civico "G.Zannato" Montecchio Maggiore (VI) 18 Dicembre 1997 , pp. 39 - 43
        • Valdagno
          • Cerealto
    Boscardin, M., Checchi, A., Filippi, F., Guglielmino, S., Pegoraro, S., Pretto, G., Zattra, A. (1998): Offretite del Veneto. Rivista Mineralogica Italiana, 1/1998, 25-30.
    Poland
     
    • Lower Silesia (Dolnośląskie)
      • Jawor District
    Eligiusz Szełęg private collection
    Spain
     
    • Canary Islands
      • Las Palmas Province
        • Fuerteventura
    Tschernich, R. (1992): Zeolites of the World, p. 101, 192, 362, 386, 415.
        • Lanzarote
          • Playa Blanca
    Tschernich, R. (1992): Zeolites of the World, p. 52, 101, 301, 323, 362, 386, 415, 493.
    UK
     
    • Scotland
      • North West Highlands (Inverness-shire)
        • Isle of Skye
          • Duirinish
            • Dunvegan
    No reference listed
          • Trotternish
            • Staffin
              • Flodigarry
    BMS Database
      • Strathclyde (Ayrshire)
        • Beith
    [BMS]
      • Strathclyde (Renfrewshire)
    BMS Database
    USA
     
    • Arizona
      • Greenlee Co.
        • Shannon Mts
          • Clifton-Morenci District
            • Clifton
              • San Francisco River area
    Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 316.
      • Maricopa Co.
        • Phoenix
      • Yavapai Co.
    Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 314.
    • California
      • Del Norte Co.
    Tschernich, 1992. Zeolites of the World, p.164.
      • Los Angeles Co.
    Mineral News v.14 no.9
    • Colorado
      • Jefferson Co.
        • Golden District
          • Golden
    Rocks & Minerals 79:4
    MinRec 19:153
    • Idaho
      • Ada Co.
    Tschernich, R. (1992): Zeolites of the World, 115
      • Adams Co.
    Ream, Lanny R. 2004. Idaho Minerals, 2nd edition, Revised and Updated
      • Idaho Co.
        • Skookumchuck Creek
    Ream, Lanny R. 2004. Idaho Minerals, 2nd edition, Revised and Updated
    • Nevada
    NBMG Spec. Pub. 31 Minerals of Nevada
    • New Jersey
      • Hudson Co.
        • Secaucus
    Minerals of Laurel Hill, Secaucus, NJ, Facciolla, N.W. (published privately).
    • New Mexico
      • Grant Co.
    Northrop, Minerals of New Mexico, 3rd. rev. ed. (1996)
    Minerals of New Mexico 3rd ed.
    Minerals of New Mexico 3rd ed.
    • Oregon
      • Clackamas Co.
    Micro Probe Vol. 6 No. 4; Tschernich, R. (1992): Zeolites of the World, 116
    Micro Probe Volume VI Number 4
      • Columbia Co.
        • Goble
    Micro Probe Vol. 6 No. 5 Fall 1987; Tschernich, R. (1992): Zeolites of the World, 117
      • Grant Co.
        • Mount Vernon
    Micro Probe Volume VI Number 4
        • North Fork John Day River
    Tschernich, R. (1992): Zeolites of the World, 118
        • Ritter
    Micro Probe Volume VII Number 8 Fall 1993
    Micro Probe Volume VII Number 8 Fall 1993
      • Lake Co.
    Micro Probe Vol. 7 No. 9 Spring 1994; Tschernich, R. (1992): Zeolites of the World, 118
        • Lakeview
    Micro Probe Volume VI Number 4
      • Malheur Co.
        • Lake Owyhee State Park
    Tschernich, R. (1992): Zeolites of the World, 70
      • Wheeler Co.
        • Spray
    Micro Probe Vol. 6 No. 4; Tschernich, R. (1992): Zeolites of the World, 118
    • Washington
      • Cowlitz Co.
    Micro Probe Vol.7 No.9 Spring '94
        • Wolf Point
    Micro Probe Vol. 7 No. 10
      • Douglas and Chelan Co. Border
    Minerals of Washington, Bart Cannon 1975
      • Grays Harbor Co.
        • Porter
    Micro Probe Vol. 7 No. 5 Spring '92
      • Thurston Co.
        • Black Hills
    Zeolites of the World, R. Tschernich, 1991
    Mineral and/or Locality
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