Bredigite Mineral Data

General Bredigite Information

Chemical Formula:

Ca7Mg(SiO4)4

Composition:

Molecular Weight = 673.18 gm

Calcium 41.67 % Ca 58.31 % CaO

Magnesium 3.61 % Mg 5.99 % MgO

Silicon 16.69 % Si 35.70 % SiO₂

Oxygen 38.03 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₇Mg(SiO₄)₄

Environment:

In contact metamophosed limestones and dolostones intruded by diabase.

IMA Status:

Valid Species (Pre-IMA) 1948

Locality:

In the USA, at Marble Canyon, Culberson Co., Texas. In Ireland, at Scawt Hill and Ballycraigy, near Larne, Co. Antrim. Link to MinDat.org Location Data.

Name Origin:

For Max Albrecht Bredig (1902- ), physical chemist, who studied the polymorphism of Ca2SiO4.

Name Pronunciation:

Bredigite + Pronunciation

Synonym:

ICSD 9828

PDF 36-399

Bredigite Image

Images:

Bredigite Spurrite

Comments: White veins of bredigite in massive gray spurrite (slabbed specimen).
Location: Camphouse, Ardnamurchan, Argyll, Highland, Scotland. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Bredigite Crystallography

Axial Ratios:

a:b:c =0.5948:1:0.3674

Cell Dimensions:

a = 10.909, b = 18.34, c = 6.739, Z = 4; V = 1,348.28 Den(Calc)= 3.32

Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: P 2nn

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

By Intensity(I/I_o): 2.663(1), 2.73(1), 2.259(0.8),

Crystal Structure:

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Moore P B , Araki T , American Mineralogist , 61 (1976) p.74-87, The crystal structure of bredigite and the genealogy of some alkaline earth, orthosilicates

Physical Properties of Bredigite

Cleavage:

{130} Distinct

Color:

Colorless, Gray.

Density:

3.4

Diaphaneity:

Transparent

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Bredigite

Gladstone-Dale:

CI meas= -0.011 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.036 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2162,KPDmeas= 0.2111,KC= 0.2087
Ncalc = 1.69 - 1.71

Optical Data:

Biaxial (+), a=1.712, b=1.716, g=1.725, bire=0.0130, 2V(Calc)=68, 2V(Meas)=30.

Calculated Properties of Bredigite

Electron Density:

Bulk Density (Electron Density)=3.39 gm/cc
note: Specific Gravity of Bredigite =3.40 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Bredigite= 5.82 barns/electron
U=PE_Bredigite x rElectron Density= 19.77 barns/cc.

Radioactivity:

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

Bredigite Classification

Dana Class:

51.04.01.01 (51)Nesosilicate Insular SiO4 Groups Only

(51.04)with cations in [6] and >[6] coordination

(51.04.01)Dana Group

51.04.01.01 Bredigite Ca7Mg(SiO4)4 P 2nn mm2

Strunz Class:

09.AD.20 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AD -Nesosilicates without additional anions;

09.AD.20 Bredigite Ca7Mg(SiO4)4 P 2nn mm2

Other Bredigite Information

References:

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

See Also:

Links to other databases for Bredigite :
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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Print or Cut-and-Paste your Bredigite Specimen Label here :

Bredigite

Ca7Mg(SiO4)4
Dana No: 51.04.01.01 Strunz No: 09.AD.20
Locality:

Notes: