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Ammonioborite
A valid IMA mineral species - grandfathered
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About Ammonioborite
Formula:
(NH4)2[B5O6(OH)4]2 · H2O
Colour:
White; colourless in transmitted light
Specific Gravity:
1.765
Crystal System:
Monoclinic
Name:
In allusion to the composition, containing AMMONIum and being a BORate.
Type Locality:
Dimorph of:
Microscopic plates, grouped in parallel; commonly as fine-grained granular masses.
Unique Identifiers
Mindat ID:
204
Long-form identifier:
mindat:1:1:204:0
IMA Classification of Ammonioborite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(N3-H4)3B15O20(OH)8·4H2O
Classification of Ammonioborite
6.EA.15
6 : BORATES
E : Pentaborates
A : Neso-pentaborates
6 : BORATES
E : Pentaborates
A : Neso-pentaborates
26.5.3.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
5 : Pentaborates
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
5 : Pentaborates
9.1.15
9 : Borates
1 : Borates of the alkalis and boric acid
9 : Borates
1 : Borates of the alkalis and boric acid
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 |
|---|---|---|
| Abo | 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 Ammonioborite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Ammonioborite
Transparency:
Translucent
Colour:
White; colourless in transmitted light
Streak:
White
Cleavage:
None Observed
Density:
1.765(4) g/cm3 (Measured) 1.76 g/cm3 (Calculated)
Optical Data of Ammonioborite
Type:
Biaxial (+)
RI values:
nα = 1.47 nβ = 1.487 nγ = 1.54
2V:
Measured: 60° , Calculated: 62°
Max. Birefringence:
δ = 0.070
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:
Moderate (negative)
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:
relatively weak
Optical Extinction:
Z ∧ elongation ≃ 7°–13°; Y = b.
Chemistry of Ammonioborite
Mindat Formula:
(NH4)2[B5O6(OH)4]2 · H2O
Element Weights:
Elements listed:
Crystallography of Ammonioborite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Cell Parameters:
a = 25.27 Å, b = 9.65 Å, c = 11.56 Å
β = 94.29°
β = 94.29°
Ratio:
a:b:c = 2.619 : 1 : 1.198
Unit Cell V:
2,811.07 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Compact, fine-grained masses. Partially as platy microscopic crystals, frequently grouped in parallel position.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
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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
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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) |
|---|---|---|---|---|---|---|---|
| 0015421 | Ammonioborite | Merlino S, Sartori F (1971) Ammonioborite: New borate polyion and its structure Science 171 377-379 | 1971 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.16 Å | (100) |
| 3.09 Å | (100) |
| 5.70 Å | (60) |
| 2.876 Å | (60) |
| 3.01 Å | (50) |
| 8.98 Å | (40) |
| 5.44 Å | (30) |
Comments:
Synthetic.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals | |
| 57 : Other minerals formed by human processes |
Type Occurrence of Ammonioborite
General Appearance of Type Material:
Granular, white, and lustrous, forming a compact mass with sassolite.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 93756, 94172, R6167.
Geological Setting of Type Material:
Boric acid fumaroles in a volcanic region. In boric acid-rich fumarolic lagoons.
Associated Minerals at Type Locality:
Other Language Names for Ammonioborite
Dutch:Ammonioboriet
French:Ammonioborite
German:Ammonioborit
Norwegian:Ammonioboritt
Spanish:Ammonioborita
Related Minerals - Strunz-mindat Grouping
| 6.EA.05 | Sborgite | Na[B5O6(OH)4] · 3H2O |
| 6.EA.05 | Leucostaurite | Pb2[B5O9]Cl · 0.5H2O |
| 6.EA.10 | Ramanite-(Rb) | Rb[B5O6(OH)4] · 2H2O |
| 6.EA.10 | Ramanite-(Cs) | Cs[B5O6(OH)4] · 2H2O |
| 6.EA.10 | Santite | K[B5O6(OH)4] · 2H2O |
| 6.EA.25 | Ulexite | NaCa[B5O6(OH)6] · 5H2O |
Other Information
Notes:
Slowly and completely soluble in cold water.
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 Ammonioborite
mindat.org URL:
https://www.mindat.org/min-204.html
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Please feel free to link to this page.
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References for Ammonioborite
Localities for Ammonioborite
Showing 1 localities.
ⓘ - 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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
- 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.
Italy (TL) | |
| D'Achiardi G. (1932) +3 other references |
Quick NavTopAbout AmmonioboriteUnique IdentifiersIMA Classification Classification Mineral SymbolsPronunciation Physical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesStrunz-MindatOther InformationInternet Links References Localities
Larderello, Pomarance, Pisa Province, Tuscany, Italy