Holtite Mineral Data

General Holtite Information

Chemical Formula:

Al6(Al,Ta)(BO3)[(SiO4,SbO4,AsO4)]3(O,OH)3

Composition:

Molecular Weight = 2,589.58 gm

Tantalum 10.48 % Ta 12.80 % Ta₂O₅

Aluminum 24.17 % Al 45.67 % Al₂O₃

Iron 0.22 % Fe 0.28 % FeO

Silicon 11.50 % Si 24.59 % SiO₂

Boron 1.59 % B 5.11 % B₂O₃

Antimony 5.64 % Sb 7.50 % Sb₂O₅

Arsenic 2.03 % As 3.11 % As₂O₅

Hydrogen 0.08 % H 0.73 % H₂O

Oxygen 44.30 % O

______ ______

100.00 % 99.78 % = TOTAL OXIDE

Empirical Formula:

Al_23.2Ta_1.5Fe²⁺_0.1B_3.8Si_10.6Sb_1.2As_0.7O_69.6(OH)_2.1

Environment:

As coatings on stibiotantalite and replacing tantalite in a pegmatite.

IMA Status:

Approved IMA 1971

Locality:

At Bunbury Gully, Greenbushes, Western Australia. Link to MinDat.org Location Data.

Name Origin:

Named for Harold Edward Holt (1908-1967), Prime minister of Australia (1966-1967).

Name Pronunciation:

Holtite

Synonym:

ICSD 66143

PDF 25-1209

Holtite Image

Images:

Holtite

Comments: Pale violet crystalline granular holtite in pegmatite.
Location: Vasin-Myl'k Mountain, Voron'i Tundry, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Holtite Crystallography

Axial Ratios:

a:b:c =0.3943:1:1.7134

Cell Dimensions:

a = 4.6914, b = 11.896, c = 20.383, Z = 1; V = 1,137.55 Den(Calc)= 3.78

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P nma

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 10.28(1), 2.94(0.4), 5.89(0.34),

Crystal Structure:

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drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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H - Help Screen
I - Data Info
A - Atoms On/Off
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Help on Above

Hoskins B F , Mumme W G , Pryce M W , Mineralogical Magazine , 53 (1989) p.457-463, Holtite, (Si2.25Sb0.75)B[Al6(Al0.43 Ta0.27[]0.30)O15(O,OH)2.25]:, crystal structure and crystal chemistry, Locality: Greenbrushes, Australia

Physical Properties of Holtite

Cleavage:

{001} Distinct

Color:

Beige white, Brown, Greenish, Greenish brown, Light brown white.

Density:

3.6 - 3.9, Average = 3.75

Diaphaneity:

Semitransparent

Habit:

Blocky - Crystal shape tends to be equant (e.g. feldspars).

Habit:

Pseudo Hexagonal - Crystals show a hexagonal outline.

Hardness:

8.5 - Chrysoberyl

Luminescence:

Fluorescent, Short UV=bright yellow, Long UV=dull orange.

Luster:

Vitreous - Resinous

Streak:

white

Optical Properties of Holtite

Gladstone-Dale:

CI meas= -0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.001 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1953,KPDmeas= 0.1968,KC= 0.1955
Ncalc = 1.7 - 1.76

Optical Data:

Biaxial (-), a=1.705-1.746, b=1.728-1.759, g=1.73-1.761, bire=0.0150-0.0250, 2V(Calc)=32-42, 2V(Meas)=20-55. Dispersion r < v.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

yellow.

Calculated Properties of Holtite

Electron Density:

Bulk Density (Electron Density)=3.62 gm/cc
note: Specific Gravity of Holtite =3.78 gm/cc.

Fermion Index:

Fermion Index = 0.0087965282
Boson Index = 0.9912034718

Photoelectric:

PE_Holtite= 132.55 barns/electron
U=PE_Holtite x rElectron Density= 480.27 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Holtite is Not Radioactive

Holtite Classification

Dana Class:

54.01.03.01 (54)Nesosilicate Borosilicates and Some Beryllosilicates

(54.01)with (BO3)

(54.01.03)Dana Group

54.01.03.01 Holtite Al6(Al,Ta)(BO3)[(SiO4,SbO4,AsO4)]3(O,OH)3 P nma 2/m 2/m 2/m

Strunz Class:

09.AJ.10 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AJ -Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra,

09.AJ.10 Dumortierite Al6.5-7(BO3)(SiO4)3(O,OH)3 Pcmn 2/m 2/m 2/m

09.AJ.10 Holtite Al6(Al,Ta)(BO3)[(SiO4,SbO4,AsO4)]3(O,OH)3 P nma 2/m 2/m 2/m

09.AJ.10 Magnesiodumortierite (Mg,Ti,[])<1(Al,Mg)2Al4Si3O18-y(OH)yBy=2-3 Pmcn 2/m 2/m 2/m

Other Holtite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

See Also:

Links to other databases for Holtite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Ask about Holtite here :
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Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Holtite Specimen Label here :

Holtite

Al6(Al,Ta)(BO3)[(SiO4,SbO4,AsO4)]3(O,OH)3
Dana No: 54.01.03.01 Strunz No: 09.AJ.10
Locality:

Notes: