Hellandite-(Ce)

(Ca,REE)4Ce2Al◻2(B4Si4O22)(OH)2
IMA status
  • Approved
IMA symbol
Hld-Ce
IMA approved
2001
Also known as
  • Hellandiet-(Ce)
  • IMA2001-019

Where it forms, where it's found

Geological setting

In miarolitic cavities.

Type locality
Campo Padella
  1. Capranica
  2. Viterbo Province
  3. Lazio
  4. Italy

42.2787°, 12.1506°

7recorded occurrences
Source · OpenStreetMap

Physical

Transparency
Transparent
Colour
Light green

Crystallography

Crystal system
Monoclinic
Cell parameters
a = 19.068(8) Å · b = 4.745(2) Å · c = 10.289(3) Å
Cell angles
β = 111.18(3) °
Ratio a:b:c
1 : 0.249 : 0.540
Type-locality form

Crystals are euhedral, transparent, light-green colored, with a maximum dimension of 0.3–0.4 mm. Also found in the ground-mass of ejectum filling voids and fractures in the rock and systematically intergrown with britholite.

Comment

Space group P2/a. Cell data for Th-U-rich, Y-poor hellandite-(Ce) (Oberti et al., 1999).

Crystal structure

Synonyms

  • Hellandiet-(Ce)
  • IMA2001-019

In other languages

German
Hellandit-(Ce) · IMA 2001-019
Italian
Hellandite- · Hellandite-(Ce)

Classification

Strunz
10th ed.

9.DK.20

  • 9SilicatesClass
  • 9.DInosilicatesDivision
  • 9.DKInosilicates with 5-periodic single chainsGroup
  • 9.DK.20Hellandite-(Ce)Species

Group, growth & confusion

In the same group
6 members

Literature, links & citation

Citations
  1. 1996Grew, Edward S.; Anovitz, Lawrence M. - Eds. (1996) Boron - Mineralogy, Petrology and Geochemistry. Reviews in Mineralogy Vol. 33. Mineralogical Society of America p.862
  2. 1999Oberti, Roberta, Ottolini, Luisa, Camara, Fernando, Della Ventura, Giancarlo (1999) Crystal structure of non-metamict Th-rich hellandite-(Ce) from Latium (Italy) and crystal chemistry of the hellandite-group minerals. American Mineralogist, 84 (5) 913-921 doi:10.2138/am-1999-5-626 DOI: 10.2138/am-1999-5-626
  3. 2002Oberti, Roberta, Ventura, Giancarlo Della, Ottolini, Luisa, Hawthorne, Frank C., Bonazzi, Paola (2002) Re-definition, nomenclature and crystal-chemistry of the hellandite group. American Mineralogist, 87 (5) 745-752 doi:10.2138/am-2002-5-618DOI: 10.2138/am-2002-5-618
  4. 2017Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2017) New minerals and nomenclature modifications approved in 2017, CNMNC Newsletter No 37. Mineralogical Magazine, 81 (3) 737-742 doi:10.1180/minmag.2017.081.039DOI: 10.1180/minmag.2017.081.039
  5. 2021(2021) Hellandite-(Ce). Handbook of Mineralogy. Mineralogical Society of America
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Hellandite-(Ce) — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/hellandite-ce-27087},
  note      = {Accessed 2026-05-11}
}