Larderellite
A valid IMA mineral species - grandfathered
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About Larderellite
François (Francesco) de Larderel
Formula:
(NH4)B5O7(OH)2 · H2O
Colour:
White, yellowish due to impurities; colourless in transmitted light
Specific Gravity:
1.905
Crystal System:
Monoclinic
Name:
Named in 1853 by E. Bechi in honor of François Jacques (Francesco Giacomo) de Larderel (5 August 1790, Vienne, Isère, France - 15 June 1858, Florence, Italy), an engineer and entrepreneur who promoted the industrial exploitation of geothermal vents in Tuscany, producing boric acid. He became the principal operator of the Tuscan borax works.
Type Locality:
Dimorph of:
This page provides mineralogical data about Larderellite.
Unique Identifiers
Mindat ID:
2332
Long-form identifier:
mindat:1:1:2332:6
IMA Classification of Larderellite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
N3-H4B5O7(OH)2·H2O
Classification of Larderellite
6.EB.05
6 : BORATES
E : Pentaborates
B : Ino-pentaborates
6 : BORATES
E : Pentaborates
B : Ino-pentaborates
26.5.4.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
5 : Pentaborates
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
5 : Pentaborates
9.1.14
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 |
|---|---|---|
| Ldr | 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 Larderellite
Transparency:
Translucent
Colour:
White, yellowish due to impurities; colourless in transmitted light
Streak:
White
Cleavage:
Perfect
On {001} (?) and {010} (?).
On {001} (?) and {010} (?).
Density:
1.905(4) g/cm3 (Measured) 1.887 g/cm3 (Calculated)
Optical Data of Larderellite
Type:
Biaxial (+)
RI values:
nα = 1.493(1) nβ = 1.509(1) nγ = 1.561(1)
2V:
Measured: 58° , Calculated: 56°
Max. Birefringence:
δ = 0.068
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:
none
Chemistry of Larderellite
Mindat Formula:
(NH4)B5O7(OH)2 · H2O
Element Weights:
Elements listed:
Crystallography of Larderellite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 11.64(1) Å, b = 7.62(1) Å, c = 9.45(1) Å
β = 96.75°
β = 96.75°
Ratio:
a:b:c = 1.528 : 1 : 1.24
Unit Cell V:
832.37 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Microscopic rhomboidal tablets flattened {100}. The acute plane angle of the rhombs is ~ 68°.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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Labels
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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) |
|---|---|---|---|---|---|---|---|
| 0009364 | Larderellite | Merlino S, Sartori F (1969) The crystal structure of lardellite, NH4B5O7(OH)2*H2O Acta Crystallographica B25 2264-2270 |  | 1969 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.45 Å | (50) |
| 5.44 Å | (71) |
| 5.12 Å | (50) |
| 4.70 Å | (100) |
| 2.960 Å | (71) |
| 2.921 Å | (100) |
| 2.887 Å | (100) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals | |
| 57 : Other minerals formed by human processes |
Type Occurrence of Larderellite
Place of Conservation of Type Material:
Natural History Museum, Paris, France, 100.1384, 100.1386, 100.1388.
Geological Setting of Type Material:
Boric acid fumaroles in a volcanic region.
Associated Minerals at Type Locality:
Synonyms of Larderellite
Borocalcite (in part)
Hydrous borate of lime (in part)
Other Language Names for Larderellite
Bulgarian:Лардерелит
Dutch:Larderelliet
French:Borate de Chaux
German:Larderellit
Russian:Лардереллит
Spanish:Larderellita
Related Minerals - Strunz-mindat Grouping
| 6.EB.05 | Yarzhemskiite | K[B5O7(OH)2] · H2O |
| 6.EB.10 | Ezcurrite | Na4B10O17 · 7H2O |
| 6.EB.15 | Probertite | NaCa[B5O7(OH)4] · 3H2O |
| 6.EB.20 | Tertschite | Ca4B10O19 · 20H2O |
| 6.EB.25 | Priceite | Ca2B5O7(OH)5 · H2O |
Other Information
Notes:
Decomposed by hot 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 Larderellite
mindat.org URL:
https://www.mindat.org/min-2332.html
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Please feel free to link to this page.
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References for Larderellite
Reference List:
Beudant, François-Sulpice (1832) Traité élémentaire de minéralogie. Deuxiéme Edition [Elementary Treatise on Mineralogy. Second Edition] (2nd ed.) Vol. 2 - Tome II [Volume II]. Chez Verdière. p.249 - as Borate de Chaux
Dana, James D., Brush, George Jarvis (1868) A System of Mineralogy (5th ed.). p.882p.597 - as Bechilite
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.98
Clark, J. R., Christ, C. L. (1959) Studies of borate minerals. (VII); X-ray studies of Ammonioborite, larderellite and the Potassium and ammonium pentaborate tetrahydrates. American Mineralogist, 44 (11-12) 1150-1158
Clark, Joan R. (1960) X-ray crystallography of larderellite, NH4B5O6(OH)4. American Mineralogist, 45 (9-10) 1087-1092
Localities for Larderellite
Showing 2 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.
Italy | |
| Campostrini et al. (2011) |
| D'Achiardi (1930) +4 other references |
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Larderello, Pomarance, Pisa Province, Tuscany, Italy