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 % Na2 O
Calcium 33.30 % Ca 46.59 % CaO
Magnesium 1.66 % Mg 2.75 % MgO
Aluminum 0.28 % Al 0.53 % Al2 O3
Iron 0.90 % Fe 0.27 % FeO / 0.98 % Fe2 O3
Phosphorus 20.56 % P 47.12 % P2 O5
Oxygen 40.97 % O
Fluorine 1.80 % F 1.80 % F
- %
F -0.76 % -O=F2
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Ca8.76 Na0.24 Mg0.72 Fe3+ 0.13 Al0.11 Fe2+ 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
X Ray Diffraction:
By Intensity(I/Io ): 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:
PEBobdownsite = 5.41 barns/electronU=PEBobdownsite x r Electron 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 3 m 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 3 m 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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Bobdownsite
Ca9Mg(PO3F)(PO4)6
Dana No: 38.03.04.08 Strunz No: 08.AC.45
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