Walenta, K. (1979) Admontit, ein neues Boratmineral aus der Gipslagerstätte Schildmauer bei Admont in der Steiermark (Österreich) Mineralogy and Petrology, 26 (1) 69-77 doi:10.1007/bf01081292

Classification of AdmontiteHide

Strunz-mindat (2026):

6.FA.15

6 : BORATES
F : Hexaborates
A : Neso-hexaborates

Dana 8th ed.:

26.6.3.1

26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
6 : Hexaborates

Hey's CIM Ref.:

9.2.13

9 : Borates
2 : Borates of Be and Mg

Mineral SymbolsHide

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
Amt	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 AdmontiteHide

Lustre:

Vitreous

Transparency:

Transparent, Translucent

Colour:

Colourless

Streak:

White

Hardness:

2 - 3 on Mohs scale

Cleavage:

None Observed

Fracture:

Conchoidal

Density:

1.82 g/cm³ (Measured) 1.831 g/cm³ (Calculated)

Optical Data of AdmontiteHide

Type:

Biaxial (-)

RI values:

n_α = 1.442 n_β = 1.500 n_γ = 1.504

Max. Birefringence:

δ = 0.062
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.

Thickness: 30 µm Order divisions

Rotation:

Surface Relief:

Moderate (negative)
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.

Focus:

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.

No measured or calculated 2V is on file for this mineral, so the value used here (29°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.

Thickness: 30 µm

Stage rotation: 0°

Dispersion:

not observed

Chemistry of AdmontiteHide

Mindat Formula:

MgB₆O₁₀ · 7H₂O

Element Weights:

Element	% weight
O	72.478 %
B	17.285 %
Mg	6.477 %
H	3.760 %

Calculated from ideal end-member formula.

Elements listed:

B, H, Mg, O - search for minerals with similar chemistry

Crystallography of AdmontiteHide

Crystal System:

Monoclinic

Class (H-M):

2/m - Prismatic

Space Group:

P2₁/c

Setting:

P2₁/c

Cell Parameters:

a = 12.68(2) Å, b = 10.07(2) Å, c = 11.32(2) Å
β = 109.68(10)°

Ratio:

a:b:c = 1.259 : 1 : 1.124

Unit Cell V:

1,360.99 Å³ (Calculated from Unit Cell)

Morphology:

Crystals are poorly developed or corroded, to about 1 mm, elongated along [001], flattened parallel to {100}.

Crystal StructureHide

Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4

View
CIF File Best | x | y | z | a | b | c

Rotation
Stop | Start

Labels
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)
0012333	Admontite	dal Negro A, Ungaretti L, Basso R (1976) The crystal structure of synthetic hydrated borates: (II) MgO3B2O37H2O Crystal Structure Communications 5 433-436		1976		0	293

CIF Raw Data - click here to close

data_global
_chemical_name_mineral 'Admontite'
loop_
_publ_author_name
'dal Negro A'
'Ungaretti L'
'Basso R'
_journal_name_full 'Crystal Structure Communications'
_journal_volume 5 
_journal_year 1976
_journal_page_first 433
_journal_page_last 436
_publ_section_title
;
 The crystal structure of synthetic hydrated borates: (II) MgO*3B2O3*7H2O
;
_database_code_amcsd 0012333
_chemical_formula_sum 'Mg B6 O17 H22'
_cell_length_a 12.664
_cell_length_b 10.091
_cell_length_c 11.322
_cell_angle_alpha 90
_cell_angle_beta 109.6
_cell_angle_gamma 90
_cell_volume 1363.031
_exptl_crystal_density_diffrn      1.868
_symmetry_space_group_name_H-M 'P 1 21/c 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'x,1/2-y,1/2+z'
  '-x,1/2+y,1/2-z'
  '-x,-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_U_iso_or_equiv
Mg1   0.00000   0.00000   0.00000   0.01267
Mg2   0.50000   1.00000   0.50000   0.01520
B1   0.22520   0.12770   0.01600   0.01267
B2   0.08210   0.11740  -0.20970   0.01140
B3   0.18520  -0.09540  -0.10150   0.01267
B4   0.36930  -0.05130   0.05800   0.01646
B5   0.10520  -0.07460  -0.33300   0.01646
B6   0.17350   0.32520  -0.11680   0.01520
O1   0.14210   0.11170   0.07790   0.01646
O2   0.10150  -0.13180  -0.04710   0.01773
O3  -0.02020   0.09740  -0.17520   0.01520
O4   0.47640  -0.09360   0.11520   0.02660
O5   0.17610   0.46120  -0.12480   0.02153
O6   0.08500  -0.13580  -0.44580   0.03673
O7   0.17970   0.05530  -0.10870   0.01140
O8   0.24060   0.26730  -0.00880   0.01520
O9   0.10560   0.25670  -0.21640   0.01646
O10   0.06970   0.05210  -0.32850   0.01520
O11   0.16160  -0.14670  -0.22980   0.01520
O12   0.29830  -0.13440  -0.02900   0.01773
O13   0.33360   0.07030   0.08640   0.01773
H1   0.14400   0.17000   0.13000   0.07599
H2   0.11500  -0.19800  -0.02000   0.06333
H3  -0.06600   0.16500  -0.20000   0.05066
H4   0.51300  -0.02100   0.15100   0.07599
H5   0.13200   0.49600  -0.18800   0.07599
H6   0.04200  -0.10400  -0.51900   0.08866
H7   0.65900   1.18900   0.52500   0.05066
H8   0.71300   1.04600   0.55100   0.06333
H9   0.61500   0.88800   0.73600   0.07599
H10   0.54600   0.79300   0.64300   0.07599
H11   0.62900   0.82500   0.44500   0.08866
H12   0.50900   0.77500   0.36900   0.07599
H13   0.61400   0.35900   0.81300   0.11399
H14   0.67700   0.35500   0.72300   0.07599
Wat1   0.64400   1.10240   0.51130   0.02786
Wat2   0.54240   0.85700   0.39380   0.02786
Wat3   0.58480   0.87350   0.65270   0.02660
Wat4   0.60290   0.36120   0.73470   0.03926

X-Ray Powder DiffractionHide

Powder Diffraction Data:

d-spacing	Intensity
7.60 Å	(10vb)
12.08 Å	(9)
2.68 Å	(9)
3.93 Å	(8)
5.29 Å	(7)
3.09 Å	(6)
5.72 Å	(4)

Locality:

Schildmauer quarry, Kematen, Admont, Liezen District, Styria, Austria

Reference:

Walenta, K. (1979) Admontit, ein neues Boratmineral aus der Gipslagerstätte Schildmauer bei Admont in der Steiermark (Österreich) Mineralogy and Petrology, 26 (1) 69-77 doi:10.1007/bf01081292

Geological EnvironmentHide

Paragenetic Mode(s):

Paragenetic Mode	Earliest Age (Ga)
Near-surface Processes
25 : Evaporites (prebiotic)

Type Occurrence of AdmontiteHide

Type Locality:

ⓘ Schildmauer quarry, Kematen, Admont, Liezen District, Styria, Austria

General Appearance of Type Material:

poorly developed or corroded crystals to ca. 1 mm; [001] elongation, {100} flattening

Place of Conservation of Type Material:

n.d.

Geological Setting of Type Material:

In a gypsum deposit.

Associated Minerals at Type Locality:

Anhydrite	Eugsterite	Gypsum	Hexahydrite	Löweite
Pyrite	Quartz

Reference:

Walenta, K. (1979) Admontit, ein neues Boratmineral aus der Gipslagerstätte Schildmauer bei Admont in der Steiermark (Österreich) Mineralogy and Petrology, 26 (1) 69-77 doi:10.1007/bf01081292

Synonyms of AdmontiteHide

IMA1978-012

Other Language Names for AdmontiteHide

Dutch:Admontiet

French:Admontite

German:Admontit

Italian:Admontite

Latvian:Admontīts

Norwegian:Admontitt

Russian:Адмонтит

Spanish:Admontita

Related Minerals - Strunz-mindat Grouping Hide

6.FA.05	Aksaite	Mg[B₆O₇(OH)₆] · 2H₂O	Orth. mmm(2/m2/m2/m) : Pbca
6.FA.10	Mcallisterite	Mg₂[B₆O₇(OH)₆]₂ · 9H₂O	Trig. 3m(32/m) : R3c
6.FA.20	Rivadavite	Na₆Mg[B₆O₇(OH)₆]₄ · 10H₂O	Mon. 2/m : P2₁/m
6.FA.25	Teruggite	Ca₄Mg[AsO₄]₂[B₆O₇(OH)₆]₂ · 12H₂O	Mon. 2/m : P2₁/c

Other InformationHide

Notes:

Slowly decomposed in H2O.

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 AdmontiteHide

mindat.org URL:

https://www.mindat.org/min-27.html
Please feel free to link to this page.

Search Engines:

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Look for Admontite in the Rock H. Currier Digital Library

External Links:

Look for Admontite on Webmineral

Look for Admontite on Wikipedia

Look for Admontite on Mineralien Atlas

Raman and XRD data at RRUFF project

References and PDF downloads at RRUFF project

American Mineralogist Crystal Structure Database

Handbook of Mineralogy page PDF

Mineral Dealers:

Buy from D. Joyce minerals

References for AdmontiteHide

Reference List:

Dal Negro, A., Ungaretti, L., Basso, R. (1976) The crystal structure of synthetic hydrated borates: (II) MgO*3B2O3*7H2O. Crystal Structure Communications: 5: 433-436.

Walenta, K. (1979) Admontit, ein neues Boratmineral aus der Gipslagerstätte Schildmauer bei Admont in der Steiermark (Österreich) Mineralogy and Petrology, 26 (1) 69-77 doi:10.1007/bf01081292

Fleischer, M.; Mandarino, J.A.; Pabst, A. (1980) New mineral names. American Mineralogist, 65 (1-2). 205-210

Walenta, K. (1982) Zum Chemismus von Admontit und Machatschkiit. Schweizerische Mineralogische und Petrographische Mitteilungen: 62: 177-83. [in German]

(2005) Admontite. Handbook of Mineralogy. Mineralogical Society of America

Anthony, John W., Bideaux, Richard A., Bladh, Kenneth W., Nichols, Monte C. - Eds. (2016) Handbook of Mineralogy. https://www.handbookofmineralogy.org/

Localities for AdmontiteHide

Showing 1 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the

symbol to view information about a locality. The

symbol next to localities in the list can be used to jump to that position on the map.

Hide all sections | Show all sections

Locality ListHide

- 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). ~~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.

Austria (TL)

Styria

Liezen District

Admont

Kematen

ⓘ Schildmauer quarry (TL)

Walenta (1979) +2 other references

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Admontite

About AdmontiteHide

Unique IdentifiersHide

IMA Classification of AdmontiteHide

Classification of AdmontiteHide

Mineral SymbolsHide

Physical Properties of AdmontiteHide

Optical Data of AdmontiteHide

Chemistry of AdmontiteHide

Crystallography of AdmontiteHide

Crystal StructureHide

X-Ray Powder DiffractionHide

Geological EnvironmentHide

Type Occurrence of AdmontiteHide

Synonyms of AdmontiteHide

Other Language Names for AdmontiteHide

Related Minerals - Strunz-mindat GroupingHide

Other InformationHide

Internet Links for AdmontiteHide

References for AdmontiteHide

Localities for AdmontiteHide

Locality ListHide

Related Minerals - Strunz-mindat Grouping Hide