Benitoite Mineral Data

General Benitoite Information

Chemical Formula:

BaTiSi3O9

Composition:

Molecular Weight = 413.46 gm

Barium 33.21 % Ba 37.08 % BaO

Titanium 11.58 % Ti 19.32 % TiO₂

Silicon 20.38 % Si 43.60 % SiO₂

Oxygen 34.83 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

BaTiSi₃O₉

Environment:

Compact granular natrolite veins cutting a grayish green fibrous shist interlayered with serpentine.

IMA Status:

Valid Species (Pre-IMA) 1907

Locality:

Benitoite Gem mine, head waters of the San Benito river, 1 mile south of Santa Rita Peak, San Benito County, California, USA Link to MinDat.org Location Data.

Name Origin:

Named from its locality.

Name Pronunciation:

Benitoite + Pronunciation

Synonym:

ICSD 18100

PDF 38-464

Benitoite Image

Images:

Benitoite

Comments: Benitoite crystals in a natrolite and crossite matrix.
Location: Benitoite Gem Mine, San Benito Co., California, USA. Scale: Crystal size 1.5 cm.
© John Veevaert

Benitoite Crystallography

Axial Ratios:

a:c = 1:1.47121

Cell Dimensions:

a = 6.6, c = 9.71, Z = 2; V = 366.30 Den(Calc)= 3.75

Crystal System:

Hexagonal - Ditrigonal DipyramidalH-M Symbol (6 m2) Space Group: P 6c2

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

By Intensity(I/I_o): 3.72(1), 2.742(0.75), 3.32(0.4),

Forms:

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Forms: ( 0 0 1) ( 1 2 1) ( 1 1 1) ( 1 1 0)

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Crystal Structure:

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Zachariasen W H , Zeitschrift fur Kristallographie , 74 (1930) p.139-146, The crystal structure of benitoite, BaTiSi3O9, Locality: Dallas Gem Mine, San Benito, Ca

View Additional jPOWD Structure files for Benitoite
[1]

Physical Properties of Benitoite

Cleavage:

{1011} Poor

Color:

Blue, Purple, Pink, White, Colorless.

Density:

3.6

Diaphaneity:

Transparent to translucent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

6-6.5 - Orthoclase-Pyrite

Luminescence:

Fluorescent, Short UV=blue.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Benitoite

Gladstone-Dale:

CI meas= -0.013 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.028 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2081,KPDmeas= 0.2168,KC= 0.2141
Ncalc = 1.77 - 1.8

Optical Data:

Uniaxial (+), w=1.757, e=1.804, bire=0.0470.

Calculated Properties of Benitoite

Electron Density:

Bulk Density (Electron Density)=3.34 gm/cc
note: Specific Gravity of Benitoite =3.60 gm/cc.

Fermion Index:

Fermion Index = 0.08
Boson Index = 0.92

Photoelectric:

PE_Benitoite= 146.17 barns/electron
U=PE_Benitoite x rElectron Density= 488.71 barns/cc.

Radioactivity:

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

Benitoite Classification

Dana Class:

59.01.01.02 (59)Cyclosilicate Three-Membered Rings

(59.01)anhydrous, no other anions

(59.01.01)Benitoite group

59.01.01.01 Bazirite BaZrSi3O9 P 6m2 6 m2

59.01.01.02 Benitoite BaTiSi3O9 P 6c2 6 m2

59.01.01.03 Pabstite Ba(Sn,Ti)Si3O9 P 6c2 6 m2

59.01.01.04 Wadeite K2ZrSi3O9 P 6₃/m 6/m

Strunz Class:

09.CA.05 09 - SILICATES (Germanates)

09.C - Cyclosilicates

09.CA -[Si3O9]6- 3-membered single rings (dreier-Einfachringe),

09.CA.05 Bazirite BaZrSi3O9 P 6m2 6 m2

09.CA.05 Benitoite BaTiSi3O9 P 6c2 6 m2

09.CA.05 Pabstite Ba(Sn,Ti)Si3O9 P 6c2 6 m2

Other Benitoite Information

References:

NAME( Pough60) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Benitoite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - CalTech Mineral Spectroscopy
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - GeoScienceWorld
8 - Google Images
9 - Google Scholar
10 - Handbook of Mineralogy (MinSocAm)
11 - Handbook of Mineralogy (UofA)
12 - HyperPhysics
13 - MinDAT
14 - Mineralienatlas (Deutsch)
15 - Online Mineral Museum
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - Tradeshop.com - The Rainbow of Gems
19 - WWW-MINCRYST
20 - theimage

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Ask about Benitoite here :
Ask-A-Mineralogist from the Mineralogical Society of America
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 Benitoite Specimen Label here :

Benitoite

BaTiSi3O9
Dana No: 59.01.01.02 Strunz No: 09.CA.05
Locality:

Notes: