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Unnamed (Arseniosiderite-related mineral)
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About Unnamed (Arseniosiderite-related mineral)
Formula:
Ca, Fe, As, O, H
An unnamed Ca-Fe3+-arsenate visually indistinguishable from arseniosiderite. Originally described by Walenta (1998) who later suggested a close relationship to wallkilldellite-Fe (Walenta, 2006).
The X-ray powder diffraction pattern is very similar to that of 'dehydrated yukonite' (cf. Ross & Post, 1997) and that of Unnamed (Pb-Fe-As-Cl-Si-Na-O-H).
See also yukonite.
Mechanical mixtures (intergrowths) of this mineral and arseniosiderite are known (U. Kolitsch, unpubl. data).
The X-ray powder diffraction pattern is very similar to that of 'dehydrated yukonite' (cf. Ross & Post, 1997) and that of Unnamed (Pb-Fe-As-Cl-Si-Na-O-H).
See also yukonite.
Mechanical mixtures (intergrowths) of this mineral and arseniosiderite are known (U. Kolitsch, unpubl. data).
Unique Identifiers
Mindat ID:
31363
Long-form identifier:
mindat:1:1:31363:6
Optical Data of Unnamed (Arseniosiderite-related mineral)
Type:
Uniaxial (-)
RI values:
nω = 1.88 nε = 1.73
Max. Birefringence:
δ = 0.150
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.
Pleochroism:
Strong
Comments:
X(E) ~colourless
Z(O) brown
Z(O) brown
Chemistry of Unnamed (Arseniosiderite-related mineral)
Mindat Formula:
Ca, Fe, As, O, H
Element Weights:
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.76 Å | (10) |
| 5.68 Å | (7) |
| 3.28 Å | (6) |
| 2.96 Å | (0.5) |
| 2.77 Å | (5) |
| 2.56 Å | (2) |
| 1.641 Å | (4) |
Comments:
Additional line at 2.25 (0.5b) observed for sample from Rotenbach locality.
Common Associates
Associations Based on Photo Data:
| 1 photo of Unnamed (Arseniosiderite-related mineral) associated with Parasymplesite | Fe2+3(AsO4)2 · 8H2O |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Unnamed (Arseniosiderite-related mineral)
mindat.org URL:
https://www.mindat.org/min-31363.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Unnamed (Arseniosiderite-related mineral)
Localities for Unnamed (Arseniosiderite-related mineral)
Showing 5 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Austria | |
| Kolitsch et al. (2008) |
Chile | |
| Uwe Kolitsch (powder X-ray diffraction) +1 other reference |
Germany | |
| Walenta (1998) |
| Walenta (1998) |
| Draxler et al. (05/21) |
Clara Mine, Oberwolfach, Ortenaukreis, Freiburg Region, Baden-Württemberg, Germany