Benitoite Mineral Data

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.

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

Diaphaniety:

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

Optical Data:

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

Calculated Properties of Benitoite

Electron Density:

r_electron=3.34 gm/cc
note: r_Benitoite=3.60 gm/cc.

Fermion Index

Fermion Index = 0.08385
Boson Index = 0.91615

Photoelectric:

PE_Benitoite= 146.17 barns/electron
U=PE_Benitoite x r_electron= 488.71 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Benitoite is Not Radioactive

Benitoite Classification

Dana Class:

59.1.1.2 (59)Cyclosilicate Three-Membered Rings

(59.1)anhydrous, no other anions

(59.1.1)Benitoite group

59.1.1.1 Bazirite BaZrSi3O9 P 6m2 6 m2

59.1.1.2 Benitoite BaTiSi3O9 P 6c2 6 m2

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

59.1.1.4 Wadeite K2ZrSi3O9 P 6₃/m 6/m

Strunz Class:

VIII/E.01-10 VIII - Silicates

VIII/E - Cyklosilicates, triplet rings [Si3O9]6-

VIII/E.01 - Benitoite series

VIII/E.01-10 Benitoite BaTiSi3O9 P 6c2 6 m2

VIII/E.01-20 Pabstite Ba(Sn,Ti)Si3O9 P 6c2 6 m2

VIII/E.01-30 Bazirite BaZrSi3O9 P 6m2 6 m2

VIII/E.01-40 Wadeite K2ZrSi3O9 P 6₃/m 6/m

Other Benitoite Information

References:

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

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

Benitoite

BaTiSi3O9
Dana No: 59.1.1.2 Strunz No: VIII/E.01-10
Locality:

Notes: