Mindat Logo
Home Page Log In Message Board The Mindat Directory
Register Search Pages Chat Now! (3 online) Mindat Auctions

Offretite

Big Photo

Mont Semiol (Mont Semiouse; Mont Simiouse), Montbrison, Loire, Rhône-Alpes, France
© Georges BRET

Show Offretite Photos (25)
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
mindat.org URL:http://www.mindat.org/min-2960.html
Please feel free to link to this page.

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:
  • Look for Offretite on Google
  • Look for Offretite images on Google
    • External Links:
  • Look for Offretite on Webmineral
  • Look for Offretite on Athena Mineralogy
  • Look for Offretite on Wikipedia
  • 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)
    • Mineral Dealers:
  • Fabre Minerals - search for Offretite specimens
  • Fine Minerals from Dan Weinrich Minerals
  • Search for Offretite at Thames Valley Minerals
  • Top quality minerals from Kristalle of California
  • Find Offretite on www.crystalclassics.co.uk
  • Wilensky Fine Minerals
  • Buy Fine Minerals from mineralsweb.com
  • e-Rocks - Mineral Auctions and Sales
  • The Arkenstone - Fine Minerals
  • Lapis Mineral Magazin
  • Wendel Minerals - Auktion & Shop
  • Buy Minerals and Crystals from Crystalarium.com
    • Jobs:
  • Mining & Geology Jobs

    • Page Sponsor

    Sponsorship:This page is currently not sponsored. Click here to find out how you can sponsor this page.

    Localities for Offretite

    Hide Locality List
    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.
    These maps work faster with Firefox!
    (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
    Google
     
    www.mindat.org Web
    Copyright © Jolyon & Ida Ralph 1993-2008. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register.