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Strontioborite
A valid IMA mineral species
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Formula:
Sr[B8O11(OH)4]
Colour:
Colourless
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
2.40
Crystal System:
Monoclinic
Name:
The name reflects its composition : a strontium borate.
Unique Identifiers
Mindat ID:
3807
Long-form identifier:
mindat:1:1:3807:8
Similar Names
| Strontiobaryt | A synonym of 'Strontium-bearing Baryte' |
IMA Classification of Strontioborite
Approved
Approval year:
2020
Approval history:
first discredited; then (2020) re-approved
Type description reference:
Classification of Strontioborite
6.FC.10
6 : BORATES
F : Hexaborates
C : Phyllo-hexaborates
6 : BORATES
F : Hexaborates
C : Phyllo-hexaborates
25.6.3.1
25 : ANHYDROUS BORATES CONTAINING HYDROXYL OR HALOGEN
6 : Hexaborates
25 : ANHYDROUS BORATES CONTAINING HYDROXYL OR HALOGEN
6 : Hexaborates
9.3.26
9 : Borates
3 : Borates of Ca and Sr
9 : Borates
3 : Borates of Ca and Sr
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 |
|---|---|---|
| Srbo | 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 Strontioborite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Strontioborite
Vitreous
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Hardness:
2½ on Mohs scale
Tenacity:
Very brittle
Cleavage:
Perfect
Perfect, mica-like cleavage on {100}
Perfect, mica-like cleavage on {100}
Fracture:
Step-Like
Comment:
stepped or laminated
Density:
2.40(2) g/cm3 (Measured) 2.35 g/cm3 (Calculated)
Optical Data of Strontioborite
Type:
Biaxial (+)
RI values:
nα = 1.470(2) nβ = 1.510(2) nγ = 1.579(2)
2V:
Measured: 85° (5), Calculated: 77.5°
Max. Birefringence:
δ = 0.109
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:
Low (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
Orientation:
Elongation is positive or negative (for different crystals), inclined.
Pleochroism:
Non-pleochroic
Chemistry of Strontioborite
Mindat Formula:
Sr[B8O11(OH)4]
Element Weights:
Elements listed:
Crystallography of Strontioborite
Crystal System:
Monoclinic
Class (H-M):
2 - Sphenoidal
Space Group:
P21
Setting:
P21
Cell Parameters:
a = 7.6192(3) Å, b = 8.1867(2) Å, c = 9.9164(3) Å
β = 108.357(4)°
β = 108.357(4)°
Ratio:
a:b:c = 0.931 : 1 : 1.211
Unit Cell V:
587.07 ų (Calculated from Unit Cell)
Z:
2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.22 Å | (100) |
| 5.409 Å | (61) |
| 4.090 Å | (64) |
| 3.300 Å | (48) |
| 3.082 Å | (28) |
| 2.926 Å | (25) |
| 2.121 Å | (30) |
| 2.043 Å | (37) |
Type Occurrence of Strontioborite
General Appearance of Type Material:
lamellar, scaly or tabular crystals up to 2 mm across
Place of Conservation of Type Material:
collections of the Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18-2, Moscow 119071, Russia, registration numbers 69851 (holotype) and ST-7069 (cotype)
Geological Setting of Type Material:
salt dome
Associated Minerals at Type Locality:
Synonyms of Strontioborite
Other Language Names for Strontioborite
Related Minerals - Strunz-mindat Grouping
| 6.FC.05 | Nobleite | CaB6O9(OH)2 · 3H2O |
| 6.FC.05 | Tunellite | SrB6O9(OH)2 · 3H2O |
| 6.FC.15 | Strontioginorite | CaSrB14O20(OH)6 · 5H2O |
| 6.FC.15 | Ginorite | Ca2B14O20(OH)6 · 5H2O |
| 6.FC.20 | Fabianite | CaB3O5(OH) |
Fluorescence of Strontioborite
non-fluorescent under ultraviolet light or an electron beam
Other Information
IR Spectrum:
The IR spectrum of strontioborite is unique and can be used as a reliable diagnostic tool.
Notes:
water insoluble
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 Strontioborite
mindat.org URL:
https://www.mindat.org/min-3807.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Strontioborite
Localities for Strontioborite
Showing 1 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.
Kazakhstan (TL) | |
| Handbook of Mineralogy Vol V p 6 +3 other references |
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