Sassolite
A valid IMA mineral species - grandfathered
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About Sassolite
View of the Sasso Pisano soffioni area, ca. 1920.
Sasso Pisano, Castelnuovo di Val di Cecina, Pisa Province, Tuscany, Italy
Sasso Pisano, Castelnuovo di Val di Cecina, Pisa Province, Tuscany, Italy
Formula:
H3BO3
Colour:
White to grey, occasionally colourless, yellow or brown
Lustre:
Pearly
Hardness:
1
Specific Gravity:
1.46 - 1.5
Crystal System:
Triclinic
Name:
Named after its discovery locality, Sasso, Tuscany, Italy.
This page provides mineralogical data about Sassolite.
Unique Identifiers
Mindat ID:
3540
Long-form identifier:
mindat:1:1:3540:4
IMA Classification of Sassolite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
B(OH)3
Classification of Sassolite
6.AA.05
6 : BORATES
A : Monoborates
A : BO3, without additional anions; 1(D).
6 : BORATES
A : Monoborates
A : BO3, without additional anions; 1(D).
24.3.1.1
24 : ANHYDROUS BORATES
3 : AmBn[XO3]p
24 : ANHYDROUS BORATES
3 : AmBn[XO3]p
9.1.1
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 |
|---|---|---|
| Sso | 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 Sassolite
Pearly
Transparency:
Transparent
Colour:
White to grey, occasionally colourless, yellow or brown
Streak:
White
Hardness:
1 on Mohs scale
Cleavage:
Perfect
{001} micaceous
{001} micaceous
Density:
1.46 - 1.5 g/cm3 (Measured) 1.48 g/cm3 (Calculated)
Optical Data of Sassolite
Type:
Biaxial (-)
RI values:
nα = 1.34 nβ = 1.456 nγ = 1.459
2V:
Measured: 5° , Calculated: 16°
Max. Birefringence:
δ = 0.119
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:
High (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
Optical Extinction:
X almost ⊥ {001}; OAP nearly ‖ b and ⊥ {001}.
Chemistry of Sassolite
Mindat Formula:
H3BO3
Elements listed:
Crystallography of Sassolite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 7.02 Å, b = 7.06 Å, c = 6.59 Å
α = 103.65°, β = 101.11°, γ = 59.98°
α = 103.65°, β = 101.11°, γ = 59.98°
Ratio:
a:b:c = 0.994 : 1 : 0.933
Unit Cell V:
273.72 ų (Calculated from Unit Cell)
Morphology:
Tabular crystals {001}, pseudohexagonal in development; rarely needle-lke [001]. Usually small scales; grouped in stalactitic forms at times. Coatings.
Twinning:
Common on twin axis [001].
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0009809 | Sassolite | Gajhede M, Larsen S, Rettrup S (1986) Electron density of orthoboric acid determined by X-ray diffraction at 105 K and ab initio calculations Acta Crystallographica B42 545-552 |  | 1986 | synthetic | 0 | 293 |
| 0018735 | Sassolite | Zachariasen W H (1934) The crystal lattice of boric acid, BO3H3 Zeitschrift fur Kristallographie 88 150-161 | 1934 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.18 Å | (100) |
| 6.02 Å | (10) |
| 1.590 Å | (10) |
| 5.89 Å | (<10) |
| 4.59 Å | (<10) |
| 4.20 Å | (<10) |
| 4.04 Å | (<10) |
Comments:
Furnace Creek district, California, USA. The data are from Allen and Kramer (1957).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) | |
| 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 Sassolite
Place of Conservation of Type Material:
Museum für Naturkunde, Humboldt-Universität-Berlin, Germany, 1997-4022.
Synonyms of Sassolite
Other Language Names for Sassolite
Catalan:Sassolita
Dutch:Sassoliet
French:Acide boracique
Acide borique
Acide borique
Latin:Acidum boracis
Polish:Sassolin
Russian:Сассолин
Spanish:Sassolita
Common Associates
Associations Based on Photo Data:
| 2 photos of Sassolite associated with Realgar | As4S4 |
| 2 photos of Sassolite associated with Native Sulphur | S8 |
| 1 photo of Sassolite associated with Clinometaborite | HBO2 |
| 1 photo of Sassolite associated with Metaborite | HBO2 |
| 1 photo of Sassolite associated with Augite | (CaxMgyFez)(Mgy1Fez1)Si2O6 |
| 1 photo of Sassolite associated with Salammoniac | NH4Cl |
| 1 photo of Sassolite associated with Steropesite | Tl3BiCl6 |
| 1 photo of Sassolite associated with Aiolosite | Na4Bi(SO4)3Cl |
| 1 photo of Sassolite associated with Ferruccite | Na[BF4] |
| 1 photo of Sassolite associated with Avogadrite | (K,Cs)[BF4] |
Related Minerals - Strunz-mindat Grouping
| 6.AA.15 | Nordenskiöldine | CaSn4+[BO3]2 |
| 6.AA.15 | Tusionite | Mn2+Sn4+[BO3]2 |
| 6.AA.35 | Jimboite | (Mn2+,Mg)3[BO3]2 |
| 6.AA.35 | Kotoite | Mg3[BO3]2 |
| 6.AA.40 | Takedaite | Ca3[BO3]2 |
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 Sassolite
mindat.org URL:
https://www.mindat.org/min-3540.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Sassolite
Reference List:
Klaproth, M. H. (1802) LXXX. Untersuchung des Sassolins. In Beiträge zur chemischen Kenntniss der Mineralkörper Vol. 3. Rottmann. p.95-101.
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.130
Zachariasen, W. H. (1934) The Crystal Lattice of Boric Acid, BO3H3. Zeitschrift für Kristallographie, Mineralogie und Petrographie, 88 (1-6). p.150-161. doi:10.1524/zkri.1934.88.1.150
Zachariasen, W. H. (1954) The precise structure of orthoboric acid. Acta Crystallographica, 7 (4) 305-310 doi:10.1107/s0365110x54000886
Allen, Robert D., Kramer, Henry (1957) Ginorite and sassolite from Death Valley, California. American Mineralogist, 42 (1-2) 56-61
Smith, R. L. (1958) Some new occurrences of sassolite in the United States. American Mineralogist, 43 (11-12). 1204-1205
Schwarzmann, Einhard (1962) Zusammenhang zwischen OH‐Valenzfrequenzen und OH…OH‐ bzw. OH…OH‐Abständen in festen Hydroxiden. Zeitschrift für anorganische und allgemeine Chemie, 317 (3-4). 176-185 doi:10.1002/zaac.19623170305
Localities for Sassolite
Showing 46 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.
Australia | |
| Pring et al. (2000) |
Chile | |
| TESIS PARA OPTAR AL GRADO DE MAGÍSTER ... |
| Inostroza et al. (2020) | |
| Inostroza et al. (2020) |
China | |
| Fang et al. (2024) |
Germany | |
| Sindern et al. (2005) +1 other reference |
India | |
| Walter Schumann (2008) | |
Iran | |
| Nokhbatolfoghahaei et al. (2025) |
Italy | |
| Russo et al. (2004) |
| Russo | |
| Scacchi (1849) |
| Russo et al. (2017) | |
| Pelloux (1927) +1 other reference | |
| Pellino et al. (2025) | |
| Jervis (1881) +1 other reference |
| HOLLAND |
| Allen et al. (1957) |
| Palache et al. (1951) +2 other references |
Japan | |
| - (n.d.) |
| Okano (1962) |
| Okano (1962) |
Lebanon | |
| Kruszewski (2019) |
Mozambique | |
| Thomas et al. (2010) |
Nicaragua | |
| Quisefit et al. (1989) |
Russia | |
| [Der Aufschluss 1995:4 p163-180] +1 other reference |
| [Der Aufschluss 1995:4 p163-180] | |
| Shevko et al. (2018) |
| Thomas et al. (2009) |
Serbia | |
| Putzolu et al. (2025) |
Tajikistan | |
| Thomas et al. (2010) |
USA | |
| Pemberton (1983) +1 other reference |
| Pemberton (1983) +1 other reference | |
| rruff.info (n.d.) |
| Allen et al. (1957) +5 other references |
| Erd et al. (1979) | |
| U.S. Borax |
| Smith et al. (1958) +4 other references | |
| Smith et al. (1958) +4 other references | |
| Garrett (1998) | |
| |
| Veatch (1867) +3 other references |
| |
| Smith (1958) +3 other references |
| Bailey (1902) +2 other references |
| Castor et al. (2004) |
Vietnam | |
| Le Thi-Thu Huong (2017) +2 other references |
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La Fossa crater, Vulcano Island, Lipari, Eolie Islands, Metropolitan City of Messina, Sicily, Italy