Where it forms, where it's found
- Type locality
- Mochalin Log
- Kyshtym
- Chelyabinsk Oblast
- Russia
55.8117°, 60.5628°
3recorded occurrences
Physical
- Hardness
- 1Talc
- 2Gypsum
- 3Calcite
- 4Fluorite
- 5Apatite
- 6Orthoclase
- 7Quartz
- 8Topaz
- 9Corundum
- 10Diamond
- Transparency
- Translucent
- Colour
- Green · olive-green
- Fracture
- Irregular/Uneven
- Density
- 4.805 g/cm³
Optical
- Optical type
- Biaxial (+)
- Refractive index
- 1.808 – 1.838
- Surface relief
- Very high
- Principal indices
- nα 1.808 · nβ 1.812 · nγ 1.838
- Pleochroism
- Strong
X = strong bluish green; Y = yellow-green; Z = pinkish.
- Dispersion
- relatively strong
Δ = 0Δmax
PPLpleochroism per grain
XPLindependent extinctions · rotate the stage
PPLpleochroism only · colour blends on rotation
XPLinterference colour · extinct every 90°
Retardation300 nm
Order1st order
XPL colour
Crystallography
- Cell parameters
- a = 7.74 Å · c = 8.5 Å
- Type-locality form
Rare crystals in fissures; more commonly as grains, to 3 mm, or veins in cerite; in concentrically zoned aggregates around cerite and bastnaesite.
- Comment
: [Monoclinic, pseudohexagonal] [by analogy to törnebohmite-(Ce)]
Chemical composition
Synonyms
- Törnebohmiet-(La)
In other languages
- German
- Törnebohmit-(La)
- Italian
- Törnebohmite- · Törnebohmite-(La)
Classification
Strunz
10th ed.9.AG.45
- 9SilicatesClass
- 9.ANesosilicatesDivision
- 9.AGNesosilicates with additional anions; cations in > [6] +- [6] coordinationGroup
- 9.AG.45Törnebohmite-(La)Species
Dana
8th ed.52.04.05.02
- 52Nesosilicates Insular Sio4 Groups and O, Oh, F, H2oClass
- 52.04Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] and/or >[6] coordinationType
- 52.04.05Tornebohmite groupGroup
- 52.04.05.02Törnebohmite-(La)Species
CIM
—16.13.3
- 16Silicates Containing Aluminum and other MetalsClass
- 16.13Aluminosilicates of the rare earthsGroup
- 16.13.3Törnebohmite-(La)Species
Literature, links & citation
Citations
- 1920Geijer, P. (1920) The cerium minerals of Bastnäs at Riddarhyttan. Sveriges Geologiska Undersökning Arsbok: 14(304): 1-24.
- 1921Wherry, E.T. (1921) New minerals. American Mineralogist: 6: 118-119.
- 1921Mineralogical Magazine (1921): 19: 351.
- 1962Sviajin, N.V. (1962) Tornebohmite from the alkaline province of Ural. Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva: 91: 97-99.
- 1966Levinson, A. A. (1966) A system of nomenclature for rare-earth minerals. American Mineralogist, 51 (1-2) 152-158
Cite this entry
@misc{mineral2026,
author = {Mineral Index editorial board},
title = {Törnebohmite-(La) — Mineral Index},
year = {2026},
url = {https://mineralindex.org/minerals/tornebohmite-la-3999},
note = {Accessed 2026-05-11}
}