Holtite
A valid IMA mineral species
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About Holtite
Harold Edward Holt
Formula:
(Ta0.6◻0.4)Al6BSi3O18(O,OH)2.25
Originally assumed to be Al6(Al,Ta)(SiO4,SbO4,AsO4)3(BO3)O3.
Colour:
Light buff to cream-buff, deep olive-buff, brown, russet
Lustre:
Vitreous, Resinous, Dull
Hardness:
8½
Specific Gravity:
3.60 - 3.90
Crystal System:
Orthorhombic
Member of:
Name:
Named in honor of Harold Edward Holt (5 August 1908, Stanmore, New South Wales, Australia - 17 December 1967, Cheviot Beach, Victoria, Australia), Prime Minister of Australia (1966-1967).
Note: Groat et al. (2008) give the formula (Ta,◻,Al)Al6(BO3)(Si,Sb,As)3O12(O,OH,◻)3.
Closely related to dumortierite.
Closely related to dumortierite.
Unique Identifiers
Mindat ID:
1925
Long-form identifier:
mindat:1:1:1925:1
Similar Names
| Holmite (of Johannsen) | A synonym of 'Monchiquite' |
| Holmite (of Thompson) | A synonym of Clintonite |
IMA Classification of Holtite
Classification of Holtite
9.AJ.10
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
54.1.3.1
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
1 : Borosilicates and Some Beryllosilicates with (BO3)
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
1 : Borosilicates and Some Beryllosilicates with (BO3)
17.5.26
17 : Silicates Containing other Anions
5 : Borosilicates
17 : Silicates Containing other Anions
5 : Borosilicates
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Hlt | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Hol | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Pronunciation of Holtite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Holtite
Vitreous, Resinous, Dull
Transparency:
Translucent
Comment:
Dull when weathered
Colour:
Light buff to cream-buff, deep olive-buff, brown, russet
Streak:
Light buff
Hardness:
8½ on Mohs scale
Cleavage:
Distinct/Good
Good on {001}, may be parting
Good on {001}, may be parting
Density:
3.60 - 3.90 g/cm3 (Measured)
Optical Data of Holtite
Type:
Biaxial (-)
RI values:
nα = 1.705 - 1.746 nβ = 1.728 - 1.759 nγ = 1.73 - 1.761
2V:
Measured: 20° to 55°, Calculated: 32° to 42°
Max. Birefringence:
δ = 0.015 - 0.025
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:
Very High (positive)
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:
r < v
Optical Extinction:
X = a.
Pleochroism:
Visible
Comments:
Various shades of yellow to colorless
Chemistry of Holtite
Mindat Formula:
(Ta0.6◻0.4)Al6BSi3O18(O,OH)2.25
Originally assumed to be Al6(Al,Ta)(SiO4,SbO4,AsO4)3(BO3)O3.
Originally assumed to be Al6(Al,Ta)(SiO4,SbO4,AsO4)3(BO3)O3.
Element Weights:
Common Impurities:
Ti,Fe,As,Nb,Mn,Be,Mg,Ca,Li,Na,K,Rb,Cs
Crystallography of Holtite
Polytype:
Formula:
Crystal System:
Class (H-M)
Space Group:
Space Group Setting:
Cell Parameters:
Ratio:
Unit Cell Volume (calc):
Z:
Comment:
| Holtite I | Holtite II |
|---|---|
| (Ta0.6◻0.4)Al6BSi3O18(O,OH)2.25 | (Ta0.6◻0.4)Al6BSi3O18(O,OH)2.25 |
| Orthorhombic | Orthorhombic |
| mmm(2/m2/m2/m) - Dipyramidal | mmm(2/m2/m2/m) - Dipyramidal |
| Pnma | Pnma |
| a = 4.695(1) Å, b = 11.906(3) Å, c = 20.38(3) Å | a = 4.6893(1) Å, b = 11.881(1) Å, c = 20.394(1) Å |
| a:b:c = 0.394 : 1 : 1.712 | a:b:c = 0.395 : 1 : 1.717 |
| V 1,139.21 ų (Calculated from Unit Cell) | V 1,136.22 ų (Calculated from Unit Cell) |
| 4 | 4 |
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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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) |
|---|---|---|---|---|---|---|---|
| 0019928 | Holtite | Groat L A, Grew E S, Evans R J, Pieczka A, Ercit T S (2009) The crystal chemistry of holtite Mineralogical Magazine 73 1033-1050 | 2009 | Mt. Szklana Mine, Szklary, Zabkowice, Lower Silesia, Poland | 0 | 293 | |
| 0019927 | Holtite | Groat L A, Grew E S, Evans R J, Pieczka A, Ercit T S (2009) The crystal chemistry of holtite Mineralogical Magazine 73 1033-1050 | 2009 | Greenbushes tinfield, Bridgetown-Greenbushes Shire, Australia | 0 | 293 | |
| 0019926 | Holtite | Groat L A, Grew E S, Evans R J, Pieczka A, Ercit T S (2009) The crystal chemistry of holtite Mineralogical Magazine 73 1033-1050 | 2009 | Greenbushes tinfield, Bridgetown-Greenbushes Shire, Australia | 0 | 293 | |
| 0019925 | Holtite | Groat L A, Grew E S, Evans R J, Pieczka A, Ercit T S (2009) The crystal chemistry of holtite Mineralogical Magazine 73 1033-1050 | 2009 | Voroni Tundry, Kola Peninsula, Murmanskaja Oblast, Russia | 0 | 293 | |
| 0019738 | Holtite | Kazantsev S S, Zubkova N V, Voloshin A V (2006) Refinement of composition and structure of holtite I Crystallography Reports 51 412-413 | 2006 | Voroni Tundry deposit, Kola Peninsula, Russia | 0 | 293 | |
| 0019758 | Holtite | Zubkova N V, Pushcharovskii D Y, Kabalov Y K, Kazantsev S S, Voloshin A V (2006) Crystal structure of holtite II Crystallography Reports 51 16-22 | 2006 | Kola Peninsula, Russia | 0 | 293 | |
| 0014489 | Holtite | Hoskins B F, Mumme W G, Pryce M W (1989) Holtite, (Si2.25Sb0.75)B[Al6(Al0.43 Ta0.27[]0.30)O15(O,OH)2.25]: crystal structure and crystal chemistry Mineralogical Magazine 53 457-463 |  | 1989 | Greenbrushes, Australia | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.28 Å | (100) |
| 2.94 Å | (40) |
| 5.89 Å | (34) |
| 5.93 Å | (32) |
| 5.08 Å | (32) |
| 2.338 Å | (26) |
| 5.12 Å | (24) |
Comments:
Greenbushes, Western Australia.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Geological Setting:
Pegmatites
Type Occurrence of Holtite
General Appearance of Type Material:
Intergrown prisms and acicular coatings on stibiotantalite and as parallel acicular to asbestiform replacements of tantalite. Also as hard resinous pebbles composed of parallel needles often with S-shaped contortions. Crystals to 1 mm in length.
Place of Conservation of Type Material:
The Australian Museum, Sydney, Australia, number D43778 (type).
Western Australian Museum, Perth, Australia, number MDC 550 (holotype).
Western Australian Museum, Perth, Australia, number MDC 550 (holotype).
Geological Setting of Type Material:
Alluvial pebbles.
Associated Minerals at Type Locality:
Synonyms of Holtite
Other Language Names for Holtite
Relationship of Holtite to other Species
Member of:
Other Members of Holtite Group:
| Nioboholtite | (Nb0.6◻0.4)Al6BSi3O18 | Orth. mmm(2/m2/m2/m) : Pbcm |
| Titanoholtite | (Ti0.75◻0.25)Al6BSi3O18 | Orth. mmm(2/m2/m2/m) : Pbcm |
Common Associates
Associations Based on Photo Data:
| 5 photos of Holtite associated with Elbaite | Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 5 photos of Holtite associated with Quartz | SiO2 |
| 5 photos of Holtite associated with Polylithionite | KLi2Al(Si4O10)(F,OH)2 |
| 2 photos of Holtite associated with Albite | Na(AlSi3O8) |
| 1 photo of Holtite associated with Stibiotantalite | Sb3+TaO4 |
| 1 photo of Holtite associated with Nioboholtite | (Nb0.6◻0.4)Al6BSi3O18 |
| 1 photo of Holtite associated with Titanoholtite | (Ti0.75◻0.25)Al6BSi3O18 |
Related Minerals - Strunz-mindat Grouping
| 9.AJ. | Hingganite-(Nd) | Nd2◻Be2Si2O8(OH)2 |
| 9.AJ. | Arrheniusite-(Ce) | CaMg[(Ce7Y3)Ca5](SiO4)4(Si2B3AsO18)(BO3)F11 |
| 9.AJ.05 | Ominelite | (Fe2+,Mg)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.05 | Grandidierite | (Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.10 | Dumortierite | Al(Al2O)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.10 | Nioboholtite | (Nb0.6◻0.4)Al6BSi3O18 |
| 9.AJ.10 | Titanoholtite | (Ti0.75◻0.25)Al6BSi3O18 |
| 9.AJ.10 | Magnesiodumortierite | Mg(Al2OH)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.15 | Garrelsite | Ba3NaSi2B7O16(OH)4 |
| 9.AJ.20 | 'Muromontite' | near Be2FeY2Si3O12 |
| 9.AJ.20 | Gadolinite-(Nd) | Nd2Fe2+Be2O2(SiO4)2 |
| 9.AJ.20 | Datolite | CaB(SiO4)(OH) |
| 9.AJ.20 | Melanocerite-(Ce) | (Ce,Ca)5(SiO4,BO4)3(OH,O) |
| 9.AJ.20 | Gadolinite-(Ce) | (Ce,La,Nd,Y)2Fe2+Be2Si2O10 |
| 9.AJ.20 | Gadolinite-(Y) | Y2Fe2+Be2Si2O10 |
| 9.AJ.20 | 'Unnamed (OH-analogue of Gadolinite-(Y))' | (Y,Ca)2(Fe,◻)Be2Si2O8(OH,O)2 |
| 9.AJ.20 | Hingganite-(Ce) | (Ce,REE)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Y) | (Y,REE,Ca)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Yb) | (Yb,Y,REE)2◻Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Homilite | Ca2(Fe2+,Mg)B2Si2O10 |
| 9.AJ.20 | 'Minasgeraisite-(Y)' | (Ca2Y2)◻2(Be2B2)[SiO4]4(OH)4 |
| 9.AJ.20 | Calcybeborosilite-(Y) | (Y,Ca)2(◻,Fe2+)(B,Be)2[SiO4]2(OH,O)2 |
| 9.AJ.25 | Stillwellite-(La) | LaBSiO5 |
| 9.AJ.25 | Stillwellite-(Ce) | (Ce,La,Ca)BSiO5 |
| 9.AJ.30 | Cappelenite-(Y) | Ba(Y,Ce)6Si3B6O24F2 |
| 9.AJ.35 | Laptevite-(Ce) | Ca6(Fe2+,Mn2+)Y3REE7(SiO4)3(PO4)(B3Si3O18)(BO3)F11 |
| 9.AJ.35 | Proshchenkoite-(Y) | Ca(Y,REE,Ca,Na,Mn)15Fe2+(P,Si)Si6B3O34F14 |
| 9.AJ.35 | Okanoganite-(Y) | (Na,Ca)3(Y,Ce)12Si6B2O27F14 |
| 9.AJ.35 | Hundholmenite-(Y) | (Y,REE,Ca,Na)15(Al,Fe3+)(CaxAs3+1-x)(Si,As5+)Si6B3(O,F)48 |
| 9.AJ.35 | Vicanite-(Ce) | (Ca,Ce,La,Th)15As5+(As3+0.5,Na0.5)Fe3+Si6B4O40F7 |
| 9.AJ.40 | Jadarite | LiNaSiB3O7(OH) |
Fluorescence of Holtite
Dull orange (SW UV) and bright yellow (LW UV).
Other Information
Thermal Behaviour:
Becomes colourless on heating to 800°C.
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 Holtite
mindat.org URL:
https://www.mindat.org/min-1925.html
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Please feel free to link to this page.
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References for Holtite
Reference List:
Pryce, M. W. (1971) Holtite: a new mineral allied to dumortierite. Mineralogical Magazine, 38 (293) 21-25 doi:10.1180/minmag.1971.038.293.02
Hoskins, B. F., Mumme, W. G., Pryce, M. W. (1989) Holtite, (Si2.25Sb0.75)B [Al6(Al0.43Ta0.27□0.30) O15 (O,OH)2.25]: crystal structure and crystal chemistry. Mineralogical Magazine, 53 (372) 457-463 doi:10.1180/minmag.1989.053.372.05
Jambor, John L., Grew, Edward S. (1990) New Mineral Names. American Mineralogist, 75 (7-8) 931-937 p.937
Kazantsev, S. S., Pushcharovsky, D. Yu., Pasero, M., Merlino, S., Zubkova, N. V., Kabalov, Yu. K., Voloshin, A. V. (2005) Crystal structure of holtite I. Crystallography Reports, 50 (1) 42-47 doi:10.1134/1.1857243
Zubkova, N. V., Pushcharovskiĭ, D. Yu., Kabalov, Yu. K., Kazantsev, S. S., Voloshin, A. V. (2006) Crystal structure of holtite II. Crystallography Reports, 51 (1) 16-22 doi:10.1134/s1063774506010044
Localities for Holtite
Showing 6 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.
Argentina | |
| Galliski et al. (2012) |
Australia | |
| Jacobson et al. (2007) |
| Pryce (1971) |
Poland | |
| Pieczka (2000) +5 other references |
| Pieczka et al. (2001) | |
Russia | |
| Voloshin et al. (1976) +4 other references |
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Vasin-Myl'k Mt, Voron'i Tundry, Murmansk Oblast, Russia