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Uranopilite
A valid IMA mineral species - grandfathered
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About Uranopilite
Formula:
(UO2)6(SO4)O2(OH)6 · 14H2O
Water content appears to be variable (12-14H2O).
Colour:
Bright yellow, straw-yellow; colourless to light yellow in transmitted light.
Lustre:
Silky, Earthy
Specific Gravity:
3.7 - 4.0
Crystal System:
Triclinic
Name:
The name reflects its composition and habit, containing URANium plus Greek πίλος = "PILos" "felt", alluding to its felt-like appearance.
May dehydrate to Meta-uranopilite.
Identification and Analysis
May appear very similar to other common uranium secondary minerals including uranophane, zippeite, natrozippeite, and others.
Identification and Analysis
May appear very similar to other common uranium secondary minerals including uranophane, zippeite, natrozippeite, and others.
Unique Identifiers
Mindat ID:
4108
Long-form identifier:
mindat:1:1:4108:5
Similar Names
| Uranosilite | A valid IMA mineral species | UO3 · 7SiO2 |
| β-uranopilite | A synonym of Metauranopilite |
IMA Classification of Uranopilite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(U6+O2)6S6+O4O2(OH)6·14H2O
Classification of Uranopilite
7.EA.05
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
E : Uranyl sulfates
A : Without cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
E : Uranyl sulfates
A : Without cations
31.2.6.1
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
2 : (AB)6(XO4)Zq·xH2O
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
2 : (AB)6(XO4)Zq·xH2O
25.8.9
25 : Sulphates
8 : Sulphates of Sb, V, Cr and U
25 : Sulphates
8 : Sulphates of Sb, V, Cr and U
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 |
|---|---|---|
| Up | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Uranopilite
Silky, Earthy
Transparency:
Translucent
Colour:
Bright yellow, straw-yellow; colourless to light yellow in transmitted light.
Comment:
Soft
Cleavage:
Perfect
On {010}, perfect.
On {010}, perfect.
Density:
3.7 - 4.0 g/cm3 (Measured) 3.74 g/cm3 (Calculated)
Optical Data of Uranopilite
Type:
Biaxial (+)
RI values:
nα = 1.621 - 1.623 nβ = 1.623 - 1.625 nγ = 1.632 - 1.634
2V:
Measured: 50° , Calculated: 52°
Max. Birefringence:
δ = 0.011
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:
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v to r < v strong
Pleochroism:
Visible
Comments:
X = colorless; Y = Z = yellow.
Chemistry of Uranopilite
Mindat Formula:
(UO2)6(SO4)O2(OH)6 · 14H2O
Water content appears to be variable (12-14H2O).
Water content appears to be variable (12-14H2O).
Element Weights:
Elements listed:
Crystallography of Uranopilite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 8.896(2) Å, b = 14.029(3) Å, c = 14.339(3) Å
α = 96.610(4)°, β = 98.472(4)°, γ = 99.802(4)°
α = 96.610(4)°, β = 98.472(4)°, γ = 99.802(4)°
Ratio:
a:b:c = 0.634 : 1 : 1.022
Unit Cell V:
1,726.03 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Occurs as velvety incrustations and globular or reniform masses comprised of microscopic needles or laths, elongated [001] and flattened {010}.
Comment:
Originally assumed to be monoclinic, a = 14.03(1) Å, b = 14.60(1) Å, c = 9.184(6) Å, β = 96.87(6)°.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
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Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
Uranium Mine No. 16, Háje, Příbram District, Central Bohemian Region, Czech Republic