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Jean-Baptiste-Julien d'Omalius d'Halloy(1783-1875)
Named after the Belgian geologist Jean-Baptiste d'Omalius d'Halloy, (February 16th 1783 - January 15th 1875), who discovered the mineral. He was a nobleman, a statesman, and pioneer of modern geology in Belgium. The 7-Å(ngström) refers to the layer thickness.
Note: halloysite-7Å is NOT a polytype of halloysite.
It is an approved (grandfathered) species distinct from Halloysite-10Å which contains two water molecules per formula unit.

A synonym is "metahalloysite."

See also the chemically identical kaolinite.

Classification of Halloysite-7Å

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"

9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets URL:
Please feel free to link to this page.

Type Occurrence of Halloysite-7Å

Crystallography of Halloysite-7Å

Crystal System:
Class (H-M):
m - Domatic
Cell Parameters:
a = 5.14Å, b = 8.9Å, c = 14.9Å
β = 101.9°
a:b:c = 0.578 : 1 : 1.674
Unit Cell Volume:
V 666.97 ų (Calculated from Unit Cell)
Space group Cc.

Chemical Properties of Halloysite-7Å

All elements listed in formula:

Relationship of Halloysite-7Å to other Species

9.ED.10HisingeriteFe23+(Si2O5)(OH)4 · 2H2O
9.ED.20Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
9.ED.20ChrysocollaCu2-xAlx(H2-xSi2O5)(OH)4 · nH2O
9.ED.20Neotocite(Mn,Fe,Mg)SiO3 · H2O

Other Names for Halloysite-7Å

Name in Other Languages:
Simplified Chinese:变叙永石

Other Information

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 Halloysite-7Å

Reference List:
Berthier (1826)

American Mineralogist 39 (1954), 97

American Mineralogist 40 (1955), 1110

Acta Crystallographica B31 (1975), 2851

Clays and Clay Minerals 26 (1978), 25

Powder Diffraction 4 (1989), 19

Clays and Clay Minerals (1991): 39: 113.

Handbook of Mineralogy (Anthony et al.), 2 (1995), 311

Joussein, E., Petit, S., Churchman, J., Theng, B., Righi, D., and Delvaux, B. (2005): Halloysite clay minerals — A review. Clay Minerals, 40, 383–426.

Internet Links for Halloysite-7Å

Localities for Halloysite-7Å

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
  • Lower Austria
    • Waldviertel
      • Mühldorf
        • Amstall
GOLDMANN, Christoph & LÖFFLER, Erwin (2008): Die Mineralienfundstellen des Graphitbergbaues Amstall, NÖ.- Mefos, 19/35, 4-34, A-D, Wien.
Belgium (TL)
  • Liège Province
    • Liège
Ann.Chim.Phys., sér. 2 (1826) 32, 332-335
  • Fujian Province
    • Xiamen Prefecture
      • Tong'an District
Mao Xingli and Yan Yipeng (1987): Journal of Fuzhou University, Natural Sciences Edition 15(3); Acta Petrologica et Mineralogica 11(2), 146-156 (1992)
  • Guangxi Zhuang Autonomous Region
    • Baise Prefecture
      • Pingguo Co.
Zhongcao Liang (1983): Geology and Prospecting 19(8), 24-28; Xinyu Cao and Tongjiang Tang (1986): Geology and Prospecting 22(2), 18-23
  • Hunan Province
    • Huaihua Prefecture
      • Chenxi Co.
Shu-Gen Zhang, Xiao-Hu Liu, and Jun Ding (2006): Acta Petrologica et Mineralogica [Yanshikuangwuxue Zazhi] 25(5), 433-439.
  • Jiangsu Province
    • Suzhou Prefecture
      • Huqiu District
Kecong Han and Shengyun Ma (1985): Mineral Deposits 4(2), 58-68
Czech Republic
  • Moravia (Mähren; Maehren)
    • Vysočina Region
      • Moravské Budějovice
Natural History Museum London 2015
  • Faroe Islands
    • Suðuroy Island
      • Hvalba
Weisenberger, T. B. & Spürgin, S. (2012): Die Färöer - ein geologischer Streifzug. Aufschluss 63, 173-192.
  • Rhineland-Palatinate
    • Eifel
      • Laach lake volcanic complex
        • Mendig
          • Niedermendig
Blass, G.; Graf, H.W., Neue Mineralienfunde aus der Eifel und dem Siegerland, Mineralien-Welt 10/3, 23, 1999
Blass, G.; Graf, H.W., Neue Mineralienfunde aus der Eifel und dem Siegerland, Mineralien-Welt 10/3, 23, 1999
    • Siegerland
      • Gebhardshain
        • Kausen
Wittern: "Mineralfundstellen in Deutschland", 2001
  • Attikí Prefecture (Attica; Attika)
    • Lavrion District (Laurion; Laurium)
      • Lavrion District Mines
        • Agios Konstantinos [St Constantine] (Kamariza)
Möckel, S. (2000): Strashimirit und 11 weitere Neubestimmungen aus Lavrion (GR). Lapis 25 (7-8), 74.
        • Sounion area
          • Agia Varvara Mines (St Barbara Mines)
Möckel, S. (2000): Strashimirit und 11 weitere Neubestimmungen aus Lavrion (GR). Lapis 25 (7-8), 74.
  • Jawa Island (Java Island)
    • Jawa Barat Province (West Java Province)
      • Bogor District
Milési, J.P., Marcoux, E., Sitorus, T., Simandjuntak, M., Leroy, J., and Bailly, L. (1999): Mineralium Deposita 34, 131-149.
  • Liguria
    • Genova Province
      • Genova
Ciriotti, M.E., Blaß, G. (2010): Pot-pourri 2009: Identificazioni UKiS AMI, Minerali italiani di interesse. Micro, 1/2010, 124-127
  • Sardinia
    • Cagliari Province
      • Sarroch
- Orlandi, P., Gelosa, M., Bonacina, E., Caboni, F., Mamberti, M., Tanca, G., A. et Vinci, A. (2013) : Sardignaite, gelosaite et tancaite-(Ce) : trois nouveaux minéraux de Su Seinargiu, Sarroch, Sardaigne, Italie. Le Règne Minéral, 112, 39-52.; Orlandi P., Gelosa M., Bonacina E., Caboni F., Mamberti M., Tanca G.A., Vinci A. (2015): Sette nuove specie mineralogiche della Sardegna. I minerali della mineralizzazione a molibdeno e bismuto di Su Seinargiu (CA). Riv. Mineral. Ital., 39, 2, 84-115.
New Zealand
  • Kermadec Islands
Muiruru F.G. (1985) Hot spring and rock samples from Curtis Island Volcano, Kermadec Group. Unpub. paper Geothermal Institute, University of Auckland
  • Cajamarca Department
    • Cajamarca Province
      • Cajamarca
Dill, H.G., Bosse, H.-R., Henning, K.-H., Fricke, A., and Ahrendt, H. (1997): Mineralium Deposita 32, 149-163.
  • Urals Region
    • Southern Urals
      • Orenburgskaya Oblast'
        • Dombarov District
Gorbachev, B.F., Sharapov, A.F., Lyadskii, P.V., and Shmel'kov, N.T. (2004): The South Ushkoty Eluvial Kaolin Deposit in the Southeastern Orenburg Region. Lithology and Mineral Resources 39(5), 412-424.
        • Svetlyi
          • Buruktal District
            • Buruktal massif
Talovina, I.V., Lazarenkov, V.G., and Vorontsova, N.I. (2003): Lithology and Mineral Resources 38(5), 403-415.
  • Alabama
    • De Kalb Co.
Thomas F.Bates,Fred A.Hilderband and Ada Swineford (1950) Morphology and Structure of Endellite and Halloysite.The American Mineralogist Vol.35,July-August 1950,No.7-8
  • Maine
    • Oxford Co.
      • Paris
King, V. T. and Foord, E. E., 1994, Mineralogy of Maine, Descriptive Mineralogy, volume 1, Maine Geological Survey, Augusta, Maine, USA, pp. 418 + 88 plates.
  • North Carolina
    • Catawba Co.
Bates,Thomas F.,Hiderbrand,Fred A.,and Swineford,Ada.,(1950) Morphology and Structure of Endellite and Halloysite: The American Mineralogist,Vol.35,July-August,1950,No.7-8
Bates,Thomas F.,Hiderbrand,Fred A.,and Swineford,Ada.,(1950) Morphology and Structure of Endellite and Halloysite :The American Mineralogist ,Vol.35.July-August,1950,No.7-8
Sand,L.B.,(1954) On The Genesis of Residual Kaolins
Sand,L.B.,(1954) On The Genesis of Residual Kaolins
    • Jackson Co.
Bates,Thomas F.,Hiderbrand,Fred A.,and Swineford,Ada (1950) Morphology and Structure of Endellite and Halloysite : The American Mineralogist,Vol.35,July-Aug,1950,No.7-8
Sand,L.B.,(1954) On The Genesis of Residual Kaolins
      • Cowee Valley
        • Ellijay District
          • Franklin
Clays and Clay Minerals,39 and 113, 1991
    • Mitchell Co.
      • Spruce Pine District
        • Spruce Pine
Johnson,Sheryl L.,Guggenheim,Stephen and Van Groos,A.F Koster (1990)Thermal Stability of Halloysite by High-Pressure Differential Thermal Analysis :Clay and Clay Minerals,Vol.38,No.5,pg.477-484,1990
Sand,L.B.,(1954) On The Genesis of Residual Kaolins
    • Yancey Co.
      • Spruce Pine District
        • Celo
Sand,L.B.,(1954) On The Genesis of Residual Kaolins
  • Texas
    • Real Co.
Thomas F.Bates,Fred A.Hilderband and Ada Swineford (1950) Morphology and Structure of Endellite and Halloysite. The American Mineralogist Vol.35: July-August 1950,No.7-8
  • Utah
    • Juab Co.
      • East Tintic Mts
        • Tintic District
          • Silver City
Patterson,Sam H. and Murray.Haydn H. (1984) Kaolin,Refractory Clay,Ball Clay,and Halloysite in North America,Hawaii and the Caribbean Region : USGS Professional Paper 1306
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