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About Opal-CTHide

SiO2 · nH2O
A variety of Opal

Consists of packed microscopic (150-300 nm) spheres made up of tiny microcrystalline blades of Cristobalite and/or Tridymite, with water content as high as 10 wt%.

Pronounciation of Opal-CTHide

PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Chemical Properties of Opal-CTHide

SiO2 · nH2O

Synonyms of Opal-CTHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Bitumen12 photos of Opal-CT associated with Bitumen on mindat.org.
Quartz8 photos of Opal-CT associated with Quartz on mindat.org.
Chalcedony6 photos of Opal-CT associated with Chalcedony on mindat.org.
Cristobalite1 photo of Opal-CT associated with Cristobalite on mindat.org.
Edenite1 photo of Opal-CT associated with Edenite on mindat.org.
Hematite1 photo of Opal-CT associated with Hematite on mindat.org.

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.

Opal-CT in petrologyHide

References for Opal-CTHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Jones, J.B. and E.R. Segnit (1971) The nature of opal. I Nomenclature and constituent phases. Journal of the Geological Society of Australia: 18: 57-68.
Graetsch, H. (1994) Structural characteristics of opaline and microcrystalline silica minerals. In: Reviews in Mineralogy, Volume 29, Silica - Physical behavior, geochemistry and materials applications. Mineralogical Society of America, Washington, D.C.

Internet Links for Opal-CTHide

Localities for Opal-CTHide

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.
  • Lower Austria
    • Waldviertel
      • Brunn an der Wild
        • Atzelsdorf
Pristacz, H., jun., Kolitsch, U., Löffler, E., Knobloch, G., Prayer, A. & Thinschmidt, A. (2011): 1696) Calcit, Natrojarosit, Palygorskit, Pyrit, Siderit und andere Mineralien aus dem Marmorbruch Atzelsdorf, Brunn an der Wild, Waldviertel. Pp. 160-161 in Niedermayr, G. et al. (2011): Neue Mineralfunde aus Österreich LX. Carinthia II, 201./121., 135-186.
  • Styria
    • Bad Radkersburg
      • Klöch
Taucher, J. & Hollerer, C. E. (1998): Minerale eines Si- und Al-reichen Xenoliths aus dem Basaltsteinbruch von Klöch, Nördlicher Bruch, (Steiermark, Österreich). Mitt. naturwiss. Ver. Steiermark 128, 21-42.
    • Bruck an der Mur
      • Laming valley
        • Oberdorf an der Laming
          • Magnesite deposit
Taucher, J. (2012): „Hornstein“ aus dem Tagbau am Kaintaleck-Hohenburg, Oberdorf an der Laming, Tragößtal, Steiermark. Der Steirische Mineralog 26, 56-57.
    • Graz
      • Wildon
        • Weitendorf
Postl, W., Taucher, J. & Moser, B. (1996): Neue Mineralfunde im oststeirischen Vulkangebiet. Mitt. Abt. Miner. Landesmuseum Joanneum, 60/61, 3-76.
    • Murau
      • Katsch an der Mur
    • Stubalpe
      • Hochgössnitz
A.Weiß (1972)
  • Antofagasta
    • El Loa Province
Czech Republic
  • Central Bohemian Region
    • Benešov District
Kratochvíl, F.: Příspěvek k petrografii českého krystalinika. In Sborník geologického ústavu Československé republiky, 1947, sv. 14, s. 449-536.
  • South Moravian Region
    • Brno-Country District
      • Oslavany
        • Nová Ves
Koníčková Š., Losos Z., Hrazdil V., Houzar S., Všianský D. (2016): Mineralogie „očkových“ opálů z Nové Vsi u Oslavan (moldanubikum, Český masív). Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze 24, 1: 144-158.
  • Faroe Islands
    • Streymoy Island
      • Tórshavn
Caucia, F., Marinoni, L., Leone, A. (2013): Physical, geochemical and gemological properties of opals from Faroe Islands. Neues Jahrbuch für Mineralogie - Abhandlungen.191, 33-43
  • Auvergne-Rhône-Alpes
    • Puy-de-Dôme
      • Clermont-Ferrand
Remi Bornet Collection
Remi Bornet Collection
Aimé Rudel : "Curiosités Géologiques d'Auvergne et du Velay", Editions Volcans, 1970
      • Lempdes
Remi Bornet Collection
Remi Bornet Collection
Mallard, E., 1890, Bull. Soc. Min., v13, p. 63
Remi Bornet Collection
Remi Bornet Collection
  • Brittany
    • Ille-et-Vilaine
      • Le Pertre
BRUNET, J. (2016) - Minéralogie du Massif du Pertre, Ille-et-Vilaine. Le Règne Minéral, 127, 5-18.
  • Nouvelle-Aquitaine
    • Lot-et-Garonne
Econ Geol (1989) 84:1541-1556
  • East Macedonia and Thrace
    • Evros
      • Alexandroupoli
Voudouris, P. (2005). Mineralogy of the high-sulfidation Cu-Sb-Te Mavrokoryfi prospect (western Thrace, Greece). In Mineral Deposit Research: Meeting the Global Challenge (pp. 1435-1438). Springer, Berlin, Heidelberg.
  • North Aegean
    • Samos
Helvaci, C., Stamatakis, M. G., Zagouroglou, C., & Kanaris, J. (1993). Borate minerals and related authigenic silicates in northeastern Mediterranean Late Miocene continental basins. Exploration and Mining Geology, 2(2), 171-178.
  • South Aegean
    • Milos
      • Kimolos
        • Kimolos Island
Godelitsas, A.; Gamaletsos, P.& Roussos-Kotsis, M.(2010): Mordenite-bearing tuffs from Prassa quarry, Kimolos island, Greece. European Journal of Mineralogy. 22, 797-811
  • Southern Region
    • Bláskógabyggð
      • Haukadalur geothermal area
Jones, B., and Renaut, R.W. (2007) Microstructural changes accompanying the opal-A to opal-CT transition: New evidence from the siliceous sinters of Geysir, Haukadalur, Iceland. Sedimentology, 54, 4, 921-948.
  • Java
    • West Java Province
      • Garut
Mazot, A., Bernard, A., Sutawidjaja, I.S. (2007) Hydrothermal system of the Papandayan Volcano, West Java, Indonesia and its geochemistry evolution of thermal water after the November 2002 eruption. Jurnal Geologi Indonesia, 2:1, 15-29.
  • Negev
    • Hatrurim Formation
      • Gurim anticline
Sokol, E. V., Gaskova, O. L., Kozmenko, O. A., Kokh, S. N., Vapnik, E. A., Novikova, S. A., & Nigmatulina, E. N. (2014, November). Clastic dikes of the Hatrurim basin (western flank of the Dead Sea) as natural analogues of alkaline concretes: Mineralogy, solution chemistry, and durability. In Doklady Earth Sciences (Vol. 459, No. 1, pp. 1436-1441). Pleiades Publishing.
  • Sardinia
    • Sassari Province
Ghiara M.R., Petti C., Franco E., Lonis R., Luxoro S., Gnazzo L. (1999): Occurrence of clinoptilolite and mordenite in Tertiary calc-alkaline pyroclastites from Sardinia (Italy). Clays and Clay Minerals, 47, 3, 319-328.
  • Akita
    • Yuzawa
      • Ogachi
T. Nakanishi, E. Izawa, K. Watanabe (2003) Mineralogical and Geochemical Characteristics of Siliceous Sinter in Japan. Proceedings 25* NZ Geothermal Workshop 2003 pp155-160.
  • 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
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.
  • Atsimo-Atsinanana
    • Befotaka
      • Marovitsika Sud
        • Bemia
Simoni, M., Caucia, F., Adamao, I. & Galinetto, P. (2010): New occurrence of fire opal from Bemia, Madagascar. Gems & Gemmology. 46 (2), 114-121
  • Coahuila
    • Cuatrociénegas Municipality
      • Cuatro Ciénegas (Cuatrociénegas de Carranza; Venustiano Carranza)
        • Limestone caves
Forti, P. et al. (2006): ACTA CARSOLOGICA 35/1, 79–98.
  • Durango
    • Mapimí Municipality
Fritsch, E., Gaillou, E., Ostroumov, M., Rondeau, B., Devouard, B., Barreau, A. (2004) Relationship between nanostructure and optical absorption in fibrous pink opals from Mexico and Peru. European Journal of Mineralogy, 16, 743-752.
  • Michoacan
    • Uruapan del Progreso (Uruapan)
Fritsch, E., Gaillou, E., Ostroumov, M., Rondeau, B., Devouard, B., Barreau, A. (2004) Relationship between nanostructure and optical absorption in fibrous pink opals from Mexico and Peru. European Journal of Mineralogy, 16, 743-752
  • Kunene Region
Saphira Minerals specimens, Munich Show 2014
Pacific Ocean
  • Kermadec-Tonga trench
A. G. Reyes, C.E.J. DE Ronde, and C. W. R. Soong (2004) a Submarine Magmatic-hydrothermal System at Brothers Volcano, Kermadecs. Proceedings 26th NZ Geothermal Workshop pp 46-52
  • South California Borderland
Hein, J.R., Reid, J.A., Conrad, T.A., Dunham, R.E., Clague, D.A., Schulz, M.S., and Davis, A.S. (2010): USGS Open-File Report 10-1069
  • Arequipa
    • Caraveli Province
Fritsch, E., Gaillou, E., Ostroumov, M., Rondeau, B., Devouard, B., Barreau, A. (2004) Relationship between nanostructure and optical absorption in fibrous pink opals from Mexico and Peru. European Journal of Mineralogy, 16, 743-752.
  • Cajamarca
    • Cajamarca Province
      • Cajamarca
Dill, H.G., Bosse, H.-R., Henning, K.-H., Fricke, A., and Ahrendt, H. (1997): Mineralium Deposita 32, 149-163.
  • Lower Silesian Voivodeship
    • Ząbkowice Śląskie Co.
      • Gmina Ząbkowice Śląskie
        • Szklary
University of Adelaide, South Australia - Tate Museum collection # 22847. Ex. O.W Flörke Collection
  • Banská Bystrica Region
    • Banská Bystrica Co.
      • Ľubietová (Libetbánya; Libethen)
Mesiarkinová, M. & Ozdín, D. (2009) Study of hydrothermal SiO2 mineralization on the locality Ľubietová - Jamešná (Slovakia). Mitt. Österreich. Mineralog. Gesellschaft, 155, p. 101.
  • Košice Region
    • Michalovce Co.
Rusinová P. & Bačík P. (2013): Štruktúrna charakteristika opálu na lokalite Jovsa (Vihorlat). Esemestník, 2, 1, 17-21.
  • Aegean Region
    • Kütahya Province
      • Pazarla
Mutlu, H., Sariiz, K., and Kadir, S. (2005): Ore Geology Reviews 26, 39-50.
  • Central Anatolia Region
    • Ankara Province
Temel, A., Akdag, N., and Varol, E. (2010): Goldschmidt Conference Abstracts 2010.
  • Marmara Region
    • Balikesir Province
      • Susurluk
        • Sultançayırı (Sultan Tschair)
CAHIT HELVACI & RICARDO N. ALONSO (2000) Borate Deposits of Turkey and Argentina; A Summary and Geological Comparison. Turkish Journal of Earth Sciences, 9:1-27.
  • Colorado
    • Mineral Co.
      • Creede Mining District
Minerals of Colorado (1997) E.B. Eckel
  • Montana
    • Missoula Co.
University of Adelaide - Tate Museum collection # 22842. Ex. O.W Florke Collection
  • Oregon
    • Malheur Co.
Altaner, S.P., Grim, R.E. (1990) Mineralogy, chemistry, and Diagenesis of tuffs in the Sucker Creek Formation (Miocene), eastern Oregon. Clays & Clay Minerals 38:6, 561-572.
Franco Urbani (2009) Venezuelan Cave Minerals: Second Review. Mineralogy 1 2009 ICS Proceedings. In 15th International Congress of Speleology. p 345
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