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Gwihabaite
A valid IMA mineral species
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About Gwihabaite
Formula:
(NH4,K)NO3
Colour:
Colourless
Lustre:
Vitreous
Hardness:
2
Specific Gravity:
1.77
Crystal System:
Orthorhombic
Name:
Named after its type locality at the Gcwihaba Cave (Drotsky's Caverns), Maun, North-West District, Botswana (NOTE: The name was altered slightly to aid pronounciation - c in name stands for click sound ! of San people).
This page provides mineralogical data about Gwihabaite.
Unique Identifiers
Mindat ID:
6983
Long-form identifier:
mindat:1:1:6983:6
IMA Classification of Gwihabaite
Approved
IMA Formula:
(N3-H4)N5+O3
Approval year:
1994
First published:
1996
Classification of Gwihabaite
5.NA.15
5 : CARBONATES (NITRATES)
N : NITRATES
A : Without OH or H2O
5 : CARBONATES (NITRATES)
N : NITRATES
A : Without OH or H2O
Dana 7th ed.:
18.1.3.1
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 |
|---|---|---|
| Gwi | 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 Gwihabaite
Vitreous
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Hardness:
2 on Mohs scale
Cleavage:
None Observed
Density:
1.77 g/cm3 (Measured) 1.80 g/cm3 (Calculated)
Comment:
Measured in a mixture of tetrabromoethane and acetone.
Optical Data of Gwihabaite
Type:
Biaxial (-)
RI values:
nα = 1.458 nβ = 1.527 nγ = 1.599
2V:
Measured: 90° , Calculated: 86°
Max. Birefringence:
δ = 0.141
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:
None to Very Low
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:
none
Comments:
X = b, Y = a, Z = c
Chemistry of Gwihabaite
Mindat Formula:
(NH4,K)NO3
Elements listed:
Crystallography of Gwihabaite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 7.075 Å, b = 7.647 Å, c = 5.779 Å
Ratio:
a:b:c = 0.925 : 1 : 0.756
Unit Cell V:
312.66 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Slender prismatic crystals, divergent aggregates or "cave flowers".
Enlongated parallel to [001] and the forms are {110}, {100}, and {111}.
Enlongated parallel to [001] and the forms are {110}, {100}, and {111}.
Comment:
Space Group: P bnm
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
Black Background | White Background
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) |
|---|---|---|---|---|---|---|---|
| 0010592 | Gwihabaite | Amoros J L, Arrese F, Canut M (1962) The crystal structure of the low-temperature phase of NH4NO3(V) at -150 deg C Zeitschrift fur Kristallographie 117 92-107 |  | 1962 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.194 Å | (100) |
| 3.212 Å | (95) |
| 2.595 Å | (90) |
| 3.364 Å | (85) |
| 3.863 Å | (75) |
| 2.400 Å | (50) |
| 3.805 Å | (35) |
| 2.905 Å | (30) |
| 2.305 Å | (20) |
| 2.236 Å | (20) |
| 2.250 Å | (15) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 49 : Oxic cellular biomineralization (see also #44) | <0.54 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| 52 : Guano- and urine-derived minerals | <0.4 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) |
Geological Setting:
Caves. In bioremediated soils.
Type Occurrence of Gwihabaite
General Appearance of Type Material:
slender needles and oulopholites, up to 5 mm. long, forming efflorescences on the walls, boulders, bat guano and earthy floor of the cave
Place of Conservation of Type Material:
Type material is deposited in the Ditsong National Museum of Natural History (formerly Transvaal Museum in Pretoria).
Geological Setting of Type Material:
Caves. Bacterial decay of bat guano.
Associated Minerals at Type Locality:
Ravat village, Yagnob River, Zeravshan Range, Sughd, Tajikistan