Tritomite-(Ce)

Where it forms, where it's found

Geological setting: Nepheline syenite pegmatites.
Type locality: Låven
Larvik Commune
Vestfold
Norway
58.9956°, 9.8175°

20recorded occurrences

Source · OpenStreetMap

Physical

Hardness: 1Talc
2Gypsum
3Calcite
4Fluorite
5Apatite
6Orthoclase
7Quartz
8Topaz
9Corundum
10Diamond
Transparency: Opaque
Colour: Dark red-brown · amber · black
Streak: Yellowish grey
Tenacity: brittle
Cleavage: None Observed
Fracture: Irregular/Uneven · Conchoidal
Density: 4.15 g/cm³

Optical

Optical type: Isotropic
Surface relief: High
Principal indices: n 1.685 – 1.763
Notes: Isotropic to weakly anisotropic

Isotropy testPPL ↔ XPL diagnostic

PPL intrinsic colour; no change on stage rotation

XPL extinct at every orientation

Single index: n = 1.724

Crystallography

Cell parameters: a = 9.35 Å · c = 6.88 Å
Type-locality form: As pseudotetrahedral crystals; also as rounded aggregates.
Comment: Metamict; hexagonal after heating at 1000 ±C.

Chemical composition

Constituent elements: Mass composition breakdown
Element Atoms At. mass g/mol Mass g/mol Mass share
58CeCerium Cerium 5 140.116 700.580
56.76%
8OOxygen Oxygen 26 15.999 415.974
33.70%
14SiSilicon Silicon 3 28.085 84.255
6.83%
5BBoron Boron 3 10.810 32.430
2.63%
1HHydrogen Hydrogen 1 1.008 1.008
0.08%
Total 1234.247 100.00%
Mass share = atoms × atomic mass ÷ molar mass × 100
From IMA formula

Mass composition breakdown
Element	Atoms	At. mass g/mol	Mass g/mol	Mass share
58CeCerium	Cerium	5	140.116	700.580	56.76%
8OOxygen	Oxygen	26	15.999	415.974	33.70%
14SiSilicon	Silicon	3	28.085	84.255	6.83%
5BBoron	Boron	3	10.810	32.430	2.63%
1HHydrogen	Hydrogen	1	1.008	1.008	0.08%
	Total	1234.247	100.00%

Synonyms

Tritomiet-(Ce)
Tritomit

In other languages

German: Tritomit-(Ce)
Italian: Tritomite- · Tritomite-(Ce)

Classification

Strunz

10th ed.

9.AH.25

9SilicatesClass
9.ANesosilicatesDivision
9.AHNesosilicates with CO₃, SO₄, PO₄, etc.Group
9.AH.25Tritomite-(Ce)Species

Dana

8th ed.

54.02.05.01

54Nesosilicates Borosilicates and Some BeryllosilicatesClass
54.02Borosilicates and Some Beryllosilicates with B in [4] coordinationType
54.02.05Tritomite groupGroup
54.02.05.01Tritomite-(Ce)Species

CIM

—

17.5.22

17Silicates Containing other AnionsClass
17.5BorosilicatesGroup
17.5.22Tritomite-(Ce)Species

Group, growth & confusion

8 members

1 mineral

AstrophylliteK₂NaFe²⁺₇Ti₂(Si₄O₁₂)₂O₂(OH)₄F
Mineral
—

Literature, links & citation

Citations

1850Weibye, P. H., Berlin, N. J., Sjögren, K. A., von Borck, J. B. (1850) Neue Mineralien aus Norwegen beschrieben von P.H. Weibye; analysirt von N.J. Berlin, K.A. Sjögren und J.B. von Borck (Erster Theil) [1.Tritomit, 2. Katapleiit, 3.Atheriasit, 4. Eudnophit.]. [New minerals from Norway described by P.H. Weibye; analyzed by N.J. Berlin, K.A. Sjögren and J.B. von Borck (first part) [1.tritomite, 2. catapleiite, 3. atheriasite, 4. eudnophite.].]. Annalen der Physik und Chemie, 155. 299-304 doi:10.1002/andp.18501550210DOI: 10.1002/andp.18501550210
1856Forbes, David (1856) On the Chemical Composition of some Norwegian Minerals. Part II. The Edinburgh New Philosophical Journal, S. 2 Vol. 3. 59-65
1890Brøgger, Waldemar Christofer (1890) Die Mineralien der Syenitpegmatitgänge der südnorwegischen Augit- und Nephelinsyenite. Zeitschrift für Krystallographie und Mineralogie, 16 (1). 1-893
1957Neumann, H., Sverdrup, T., Sæbø, P.C. (1957): X-ray powder patterns for mineral identification, Ill-silicates. Norske Vidensk. Akad. Oslo, 1., Mat-Naturvit. Klasse 1957, No.6: 1-18.
1962Jaffe, Howard W., Molinski, Victor J. (1962) Spencite, the yttrium analogue of tritomite from Sussex County, New Jersey. American Mineralogist, 47 (1-2) 9-25

Cite this entry

@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Tritomite-(Ce) — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/tritomite-ce-4026},
  note      = {Accessed 2026-05-11}
}