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About Hellandite-(Ce)Hide

Amund T. Helland
(Ca,REE)4Ce2Al□2(B4Si4O22) (OH)2
In the IMA approved report on hellandites (Oberti et al., 2002), the occupancy at the T sites was given as (Be,Li)2–x, however the value of x was not specified. Actually it is always x > 1, therefore the T site is vacant in the ideal formula of hellandite-(Ce).
Light green
Crystal System:
Defined as a Ce-dominant mineral distinct from hellandite-(Y) in 2002 by R. Oberti, G. Della Ventura, L. Ottolini, F. C. Hawthorne, and P. Bonazzi.

The hellandite root is for Amund Theodor Helland (October 11, 1846 Bergen, Norway - November 15, 1918 Oslo "Kristiania", Norway), professor of geology and geography at the Royal Frederick University (University of Oslo).
The correct formula (according to the IMA Newsletter no. 37) is (Ca,REE)4Ce2Al□2(B4Si4O22)(OH)2.

Classification of Hellandite-(Ce)Hide

Approval Year:
Approval History:
Revision of formula: IMA 2017 (CNMNC Newsletter No. 37).

9 : SILICATES (Germanates)
D : Inosilicates
K : Inosilicates with 5-periodic single chains

Physical Properties of Hellandite-(Ce)Hide

Light green

Chemical Properties of Hellandite-(Ce)Hide

(Ca,REE)4Ce2Al□2(B4Si4O22) (OH)2

In the IMA approved report on hellandites (Oberti et al., 2002), the occupancy at the T sites was given as (Be,Li)2–x, however the value of x was not specified. Actually it is always x > 1, therefore the T site is vacant in the ideal formula of hellandite-(Ce).
IMA Formula:

Crystallography of Hellandite-(Ce)Hide

Crystal System:
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 19.068(8) Å, b = 4.745(2) Å, c = 10.289(3) Å
β = 111.18(3)°
a:b:c = 4.019 : 1 : 2.168
Unit Cell V:
868.04 ų (Calculated from Unit Cell)
Space group P2/a. Cell data for Th-U-rich, Y-poor hellandite-(Ce) (Oberti et al., 1999).

Type Occurrence of Hellandite-(Ce)Hide

Synonyms of Hellandite-(Ce)Hide

Other Language Names for Hellandite-(Ce)Hide

Relationship of Hellandite-(Ce) to other SpeciesHide

Other Members of this group:
Ferri-mottanaite-(Ce) Ca4Ce2Fe3+(Be1.50.5)[Si4B4O22]O2Mon. 2/m : P2/b
Hellandite-(Y)(Ca,REE)4Y2Al◻2(B4Si4O22) (OH)2Mon.
Mottanaite-(Ce)Ca4(Ce,REE)Σ2Al(Be1.50.5)Σ2[B4Si4O22]O2Mon. 2/m
Structurally related to group(s):
Hellandite GroupX4Q2ZT2[B4Si4O22]W2

Common AssociatesHide

Associated Minerals Based on Photo Data:
1 photo of Hellandite-(Ce) associated with BaddeleyiteZrO2
1 photo of Hellandite-(Ce) associated with Pyrochlore GroupA2Nb2(O,OH)6Z

Related Minerals - Nickel-Strunz GroupingHide

9.DK.05BabingtoniteCa2(Fe,Mn)FeSi5O14(OH)Tric. 1 : P1
9.DK.05MarsturiteNaCaMn3Si5O14(OH)Tric. 1 : P1
9.DK.05RhodoniteMn2+SiO3Tric. 1
9.DK.10SantaclaraiteCaMn4[Si5O14OH](OH) · H2OTric.
9.DK.20Hellandite-(Y)(Ca,REE)4Y2Al◻2(B4Si4O22) (OH)2Mon.
9.DK.20Mottanaite-(Ce)Ca4(Ce,REE)Σ2Al(Be1.50.5)Σ2[B4Si4O22]O2Mon. 2/m

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 Hellandite-(Ce)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Oberti, R., Ottolini, L., Cámara, F., and Della Ventura, G. (1999) Crystal structure refinement of non-metamict Th-rich hellandite-(Ce) from Latium (Italy) and crystal chemistry of the hellandite-group minerals. American Mineralogist: 84: 913-921.
Oberti, R., Della Ventura, G., Ottolini, L., Hawthorne, F.C., Bonazzi, P. (2002) Re-definition, nomenclature and crystal chemistry of the hellandite group. American Mineralogist: 87: 745-752. [http://ima-cnmnc.nrm.se/hellandite.pdf]
Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).
CNMNC Newsletter No. 37, Mineralogical Magazine, June 2017, Vol. 81(3), p. 742 [IMA revision of Formula]

Internet Links for Hellandite-(Ce)Hide

Localities for Hellandite-(Ce)Hide

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.
  • Lazio
    • Metropolitan City of Rome Capital
      • Sacrofano Caldera
        • Sacrofano
    • Viterbo Province
      • Capranica
Lapis 11(1999), 27; Della Ventura, G., Williams, C.T., Cabella, R., Oberti, R., Caprilli, E., Bellatreccia, F. (1999) Britholite-hellandite intergrowths and associated REE-minerals from the alkali-syenitic ejecta of the Vico volcanic complex (Latium, Italy): petrological implications bearing on REE mobility in volcanic systems. European Journal of Mineralogy, 11, 843-854; Oberti, R., Ottolini, L., Cámara, F., Della Ventura, G. (1999) Crystal structure of non-metamict Th-rich hellandite-(Ce) from Latium (Italy) and crystal chemistry of the hellandite-group minerals. American Mineralogist, 84, 913–921; Della Ventura, G. (2002) Ciprianite, mottanaite-(Ce) e hellandite-(Ce): tre nuovi minerali scoperti nel Lazio e revisione sistematica del gruppo dell'hellandite. Il Cercapietre, 1-2; http://www.gminromano.it/Cercapietre/rivista02/testo/02A01.html; Oberti, R., Della Ventura, G., Ottolini, L., Hawthorne, F.C., Bonazzi, P. (2002) Re-definition, nomenclature and crystal-chemistry of the hellandite group. American Mineralogist, 87, 745–752; Allori, R. (2003) 'Hellanditi' laziali: ciprianiite, hellandite-(Ce) e mottanaite-(Ce), tre nuove specie. Micro, 1, 0 (0-2003) notizie mineralogiche, 1-4; Ciriotti, M.E., Fascio, L., Pasero, M. (2009): Italian type minerals. Edizioni Plus – Università di Pisa, Pisa, 357 pp.
"Giorgio Bortolozzi (visual identification)". Although not analysed, the suffix -(Ce) has been attributed because all analytical data on britholites from other localities of the Vico volcanic complex show that the mineral is cerium dominant.
Di Domenico Dario
      • Vetralla
in the collection of Christof Schäfer; Signoretti, E., Carlini, R., Mattei, L. (2004): Località minori del vulcano Vicano: Pian di S. Martino, Le Carcarelle, Torre del Quercio. Il Cercapietre, 1-2, articolo 3; http://www.gminromano.it/Cercapietre/rivista04/testo/04A04.html; Carlini, R., Signoretti, E. (2016): Il Lazio Classico, minerali della zona di Vetralla: Tre Croci, Capo d’Acqua, Fosso Ricomero e Carcarelle. Fossils & Minerals Review, 2, 21-55; http://www.giovanigeologi.it/wp-content/uploads/2017/04/numero2web.pdf
American Mineralogist, Volume 91, pages 1170–-1177, 2006
Carlini, R., Signoretti, E., 2003. Località minori del vulcano Vicano: Villa S.Giovanni in Tuscia e Mazzocchio. Il Cercapietre. Not. del Gruppo Mineralogico Romano, 1-2: 33-41
  • Idaho
The Canadian Mineralogist, V 42, 2004, pp. 121-124.
Mineral and/or Locality  
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