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Rhabdophane-(La)
A valid IMA mineral species
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About Rhabdophane-(La)
Formula:
La(PO4) · H2O
La is almost always replaced by major to minor Ce and/or Nd.
Colour:
Brown, pinkish, yellowish-white
Hardness:
3½
Crystal System:
Hexagonal
Member of:
Name:
Originally named scovillite in 1883 after the Scoville ore deposit, Connecticut, USA, the locality where it was discovered. In 1884 it was considered to be a lanthanum variety of the previously described cerium-dominant rhabdophane. In 1987 the suffix/modifier was added to differentiate it from Ce and Nd dominant rhabdophanes. The modifier "-(La)" indicates the predominance of lanthanum over other REE in this species.
This page provides mineralogical data about Rhabdophane-(La).
Unique Identifiers
Mindat ID:
3398
Long-form identifier:
mindat:1:1:3398:1
Similar Names
| Rhabdophane | A synonym | |
| Rhabdophane-(Ce) | A valid IMA mineral species | Ce(PO4) · 0.6H2O |
| Rhabdophane-(Nd) | A valid IMA mineral species - grandfathered | Nd(PO4) · H2O |
| Rhabdophane-(Pb) | A synonym of 'Lead-bearing Rhabdophane-(Ce)' | |
| Rhabdophane-(Y) | A valid IMA mineral species | YPO4 · H2O |
IMA Classification of Rhabdophane-(La)
Classification of Rhabdophane-(La)
8.CJ.45
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
J : With only large cations
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
J : With only large cations
40.4.7.2
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
4 : (AB)5(XO4)2·xH2O
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
4 : (AB)5(XO4)2·xH2O
19.9.7
19 : Phosphates
9 : Phosphates of rare earths and Sc
19 : Phosphates
9 : Phosphates of rare earths and Sc
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Rha-La | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Rhabdophane-(La)
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Rhabdophane-(La)
Colour:
Brown, pinkish, yellowish-white
Hardness:
3½ on Mohs scale
Optical Data of Rhabdophane-(La)
Type:
Uniaxial (+)
RI values:
nω = 1.654 nε = 1.703
Max. Birefringence:
δ = 0.049
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Scoville Mine, Salisbury, Litchfield County, Connecticut, USA