Danburite Mineral Data

Danburite Mineral Data +

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General Danburite Information

Chemical Formula:

CaB2(SiO4)2

Composition:

Molecular Weight = 245.86 gm

Calcium 16.30 % Ca 22.81 % CaO

Silicon 22.85 % Si 48.88 % SiO₂

Boron 8.79 % B 28.32 % B₂O₃

Oxygen 52.06 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaB₂Si₂O₈

Environment:

Contact metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1839

Locality:

Danbury, Connecticut. Link to MinDat.org Location Data.

Name Origin:

Named after its location.

Synonym:

ICSD 6254

PDF 29-304

Danburite Image

Images:

Danburite

Comments: Very-fine, large, single transparent crystal of danburite with minor crystals of colorless calcite all around the base.
Location: Charcas, San Luis Potosi, Mexico. Scale: 4 x 2.5 x 9.5 cm.
© Dan Weinrich

Danburite Crystallography

Axial Ratios:

a:b:c =0.9184:1:0.8822

Cell Dimensions:

a = 8.048, b = 8.763, c = 7.731, Z = 4; V = 545.23 Den(Calc)= 3.00

Crystal System:

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

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

By Intensity(I/I_o): 3.564(1), 2.654(0.75), 2.961(0.7),

Crystal Structure:

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Phillips M W , Gibbs G V , Ribbe P H , American Mineralogist , 59 (1974) p.79-85, The crystal structure of danburite: A comparison with anorthite, albite, and, reedmergnerite

Physical Properties of Danburite

Cleavage:

[001] Poor

Color:

Colorless, White, Gray, Brownish white, Straw yellow.

Density:

2.97 - 3.02, Average = 2.99

Diaphaniety:

Transparent to translucent

Fracture:

Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.

Habit:

Disseminated - Occurs in small, distinct particles dispersed in matrix.

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

7 - Quartz

Luminescence:

Fluorescent.

Luster:

Vitreous - Greasy

Streak:

white

Optical Properties of Danburite

Gladstone-Dale:

CI meas= -0.004 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.003 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.211,KPDmeas= 0.2114,KC= 0.2104

Optical Data:

Biaxial (+/-), a=1.63, b=1.633, g=1.636, bire=0.0060, 2V(Calc)=88, 2V(Meas)=88-90. Dispersion relatively strong.

Calculated Properties of Danburite

Electron Density:

r_electron=2.98 gm/cc
note: r_Danburite=3.00 gm/cc.

Fermion Index

Fermion Index = 0.02863
Boson Index = 0.97137

Photoelectric:

PE_Danburite= 2.99 barns/electron
U=PE_Danburite x r_electron= 8.89 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Danburite is Not Radioactive

Danburite Classification

Dana Class:

56.3.1.1 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.3)with [Si2O7] with borate groups

(56.3.1)Danburite Goup

56.3.1.1 Danburite CaB2(SiO4)2 Pnam 2/m 2/m 2/m

56.3.1.2 Maleevite! BaB2Si2O8 P nma 2/m 2/m 2/m

56.3.1.3 Pekovite! SrB2Si2O8 P nma 2/m 2/m 2/m

Strunz Class:

VIII/J.08-20 VIII - Silicates

VIII/J - Tectosilicates (network) without anions unfamiliar to the tetraheders

VIII/J.08 - Reedmergnerite - Danburite series

VIII/J.08-10 Reedmergnerite NaBSi3O8 C1 1

VIII/J.08-20 Danburite CaB2(SiO4)2 Pnam 2/m 2/m 2/m

VIII/J.08-30 Pekovite! SrB2Si2O8 P nma 2/m 2/m 2/m

VIII/J.08-40 Maleevite! BaB2Si2O8 P nma 2/m 2/m 2/m

Other Danburite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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

Danburite

CaB2(SiO4)2
Dana No: 56.3.1.1 Strunz No: VIII/J.08-20
Locality:

Notes: