Bobdownsite Mineral Data

General Bobdownsite Information

Chemical Formula:

Ca9Mg(PO3F)(PO4)6

Composition:

Molecular Weight = 1,054.36 gm

Sodium 0.52 % Na 0.71 % Na₂O

Calcium 33.30 % Ca 46.59 % CaO

Magnesium 1.66 % Mg 2.75 % MgO

Aluminum 0.28 % Al 0.53 % Al₂O₃

Iron 0.90 % Fe 0.27 % FeO / 0.98 % Fe₂O₃

Phosphorus 20.56 % P 47.12 % P₂O₅

Oxygen 40.97 % O

Fluorine 1.80 % F 1.80 % F

- % F -0.76 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca_8.76Na_0.24Mg_0.72Fe³⁺_0.13Al_0.11Fe²⁺_0.04(PO₃)F(PO₄)₆

Environment:

Whitlockite group

IMA Status:

Approved IMA 2008 (Dana # Added)

Locality:

Big Fish River, Yukon Territory, Canada Link to MinDat.org Location Data.

Name Origin:

Named for Robert (Bob) Terrance Downs, Professor of Geophysics, University of Arizona, and chief advisor for the RRUFF project to collect Raman spectra of all minerals.

Synonym:

IMA2008-037

Bobdownsite Image

Images:

Bobdownsite

Comments: Colorless hexagonal tabular bobdownsite crystals in the type sample.
Location: Big Fish River, Yukon Territory, Canada. Scale: See Image.
© Rruff Database

Bobdownsite Crystallography

Axial Ratios:

a:c = 1:3.59121

Cell Dimensions:

a = 10.3224, c = 37.07, Z = 6; V = 3,420.70 Den(Calc)= 3.07

Crystal System:

Trigonal - Ditrigonal Pyramidal H-M Symbol (3m) Space Group: R 3c

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

By Intensity(I/I_o): 3.181(1), 2.858(0.58), 1.714(0.32),2.986(0.19), 3.428(0.18), 2.734(0.16), 5.176(0.16), 2.586(0.13),

Physical Properties of Bobdownsite

Color:

Colorless, White.

Diaphaneity:

Transparent

Habit:

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

Habit:

Tabular - Form dimensions are thin in one direction.

Streak:

white

Optical Properties of Bobdownsite

Optical Data:

NCalc= 1.6 - from Gladstone-Dale relationship (KC = 0.1965) where Ncalc=Dcalc*KC+1

Calculated Properties of Bobdownsite

Electron Density:

Bulk Density (Electron Density)=3.04 gm/cc
note: Specific Gravity of Bobdownsite =3.07 gm/cc.

Fermion Index:

Fermion Index = 0.0024968179
Boson Index = 0.9975031821

Photoelectric:

PE_Bobdownsite= 5.41 barns/electron
U=PE_Bobdownsite x rElectron Density= 16.47 barns/cc.

Radioactivity:

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

Bobdownsite Classification

Dana Class:

38.03.04.08 (38)Anhydrous Phosphates, etc

(38.03)(A+ B++)3 (XO4)2

(38.03.04)Whitlockite group

38.03.04.01 Whitlockite Ca9(Mg,Fe)(PO4)6(PO3OH) R 3c 3m

38.03.04.02 Strontiowhitlockite Sr7(Mg,Ca)3(PO4)6[PO3(OH)] R 3c 3m

38.03.04.03 Merrillite-(Ca)* (Ca,[])19Mg2(PO4)14 R 3c 3m

38.03.04.04 Merrillite Ca18Na2Mg2(PO4)14 R 3c 3m

38.03.04.05 Merrillite-(Y)* Ca16Y2Mg2(PO4)14 R 3c 3m

38.03.04.06 Ferromerrillite! Ca9NaFe(PO4)7 R 3c 3m

38.03.04.07 Tuite! Ca3(PO4)2 R 3m 3m

38.03.04.08 Bobdownsite! Ca9Mg(PO3F)(PO4)6 R 3c 3m

Strunz Class:

08.AC.45 08 - PHOSPHATES, ARSENATES, VANADATES

08.A - Phosphates, etc. without additional anions, without H2O

08.AC -With medium-sized and large cations

08.AC.45 Merrillite-(Ca)* (Ca,[])19Mg2(PO4)14 R 3c 3m

08.AC.45 Merrillite Ca18Na2Mg2(PO4)14 R 3c 3m

08.AC.45 Merrillite-(Y)* Ca16Y2Mg2(PO4)14 R 3c 3m

08.AC.45 Strontiowhitlockite Sr7(Mg,Ca)3(PO4)6[PO3(OH)] R 3c 3m

08.AC.45 Whitlockite Ca9(Mg,Fe)(PO4)6(PO3OH) R 3c 3m

08.AC.45 Ferromerrillite! Ca9NaFe(PO4)7 R 3c 3m

08.AC.45 Tuite! Ca3(PO4)2 R 3m 3m

08.AC.45 Bobdownsite! Ca9Mg(PO3F)(PO4)6 R 3c 3m

Other Bobdownsite Information

References:

PHYS. PROP.(RRUFF.info)

See Also:

Links to other databases for Bobdownsite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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

Bobdownsite

Ca9Mg(PO3F)(PO4)6
Dana No: 38.03.04.08 Strunz No: 08.AC.45
Locality:

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