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Bobdownsite

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About BobdownsiteHide

Dr. Robert Downs
Formula:
Ca9Mg(PO4)6(PO3F)
Colour:
Colourless, pale purple, yellow
Lustre:
Vitreous
Hardness:
5
Specific Gravity:
3.14
Crystal System:
Trigonal
Name:
Named for Bob Downs (University of Arizona)
Described as a new mineral in 2008, as the F-dominant analogue of whitlockite.
Later, in 2018, it was discredited because it was showed that it does not contain F, which was its distinguishing characteristic as a new mineral.
F-free bobdownsite is equivalent to the mineral whitlockite, although the phase probably lies along the whitlockite-merrillite join (IMA-17E).



Classification of BobdownsiteHide

Discredited
Approval Year:
2008
Approval History:
2008: Approved by IMA as Ca9Mg(PO4)6(PO3F),the F-dominant analogue of whitlockite (IMA 2008-037).
2018: Descredited by IMA (IMA 17-E).
8.AC.45

8 : PHOSPHATES, ARSENATES, VANADATES
A : Phosphates, etc. without additional anions, without H2O
C : With medium-sized and large cations
38.3.4.8

38 : ANHYDROUS NORMAL PHOSPHATES, ARSENATES, AND VANADATES
3 : (AB)3(XO4)2

Pronounciation of BobdownsiteHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of BobdownsiteHide

Vitreous
Transparency:
Transparent
Colour:
Colourless, pale purple, yellow
Streak:
White
Hardness:
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
None observed
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.14 g/cm3 (Measured)    3.16 g/cm3 (Calculated)

Optical Data of BobdownsiteHide

Type:
Uniaxial (-)
RI values:
nω = 1.625() nε = 1.622(2)
Max Birefringence:
δ = 0.003
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate

Chemical Properties of BobdownsiteHide

Formula:
Ca9Mg(PO4)6(PO3F)
Common Impurities:
Al,Fe,Na

Crystallography of BobdownsiteHide

Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
R3c
Cell Parameters:
a = 10.3224(3) Å, c = 37.070(2) Å
Ratio:
a:c = 1 : 3.591
Unit Cell V:
3420.7 ų
Z:
6
Morphology:
Tabular and rhombohedral crystals.
Twinning:
None observed.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
5.176 (16)
3.428 (18)
3.181 (100)
2.986 (19)
2.858 (58)
2.734 (16)
2.586 (13)
1.714 (32)

First Recorded Occurrence of BobdownsiteHide

General Appearance of First Recorded Material:
Colourless tabular crystals up to 2.7 cm in width.
Place of Conservation of First Recorded Material:
Part of the cotype sample has been deposited at the University of Arizona Mineral Museum (catalogue # 18820) and the RRUFF project (deposition # R050109).
Geological Setting of First Recorded Material:
Bobdownsite was found in the Lower Cretaceous bedded ironstones and shales where it occurs in an east–west-trending faulted vein.
Associated Minerals at First Recorded Locality:

Synonyms of BobdownsiteHide

Relationship of Bobdownsite to other SpeciesHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Pararobertsite7 photos of Bobdownsite associated with Pararobertsite on mindat.org.
Hydroxylapatite4 photos of Bobdownsite associated with Hydroxylapatite on mindat.org.
Gormanite2 photos of Bobdownsite associated with Gormanite on mindat.org.
Arrojadite-(KFe)2 photos of Bobdownsite associated with Arrojadite-(KFe) on mindat.org.
Kulanite2 photos of Bobdownsite associated with Kulanite on mindat.org.
Nahpoite2 photos of Bobdownsite associated with Nahpoite on mindat.org.
Quartz2 photos of Bobdownsite associated with Quartz on mindat.org.
Montgomeryite1 photo of Bobdownsite associated with Montgomeryite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

8.AC.WopmayiteCa6Na3□Mn(PO4)3(PO3OH)4 Trig. 3m : R3c
8.AC.05HowardevansiteNaCuFe2(VO4)3Tric. 1 : P1
8.AC.10Alluaudite(Na,Ca)Mn2+(Fe3+,Mn2+,Fe2+,Mg)2(PO4)3Mon.
8.AC.10Arseniopleite(Ca,Na)NaMn2+(Mn2+,Mg,Fe2+)2(AsO4)3Mon. 2/m : P2/b
8.AC.10Caryinite(Na,Pb)(Ca,Na)CaMn2+2(AsO4)3Mon. 2/m
8.AC.10Ferroalluaudite(Na,Ca)Fe2+(Fe3+,Mn2+,Fe2+)2(PO4)3
8.AC.10HagendorfiteNaCaMn2+Fe2+2(PO4)3Mon. 2/m : B2/b
8.AC.10JohilleriteNa(Mg,Zn)3Cu(AsO4)3Mon. 2/m : B2/b
8.AC.10Maghagendorfite(□,Na,)(Na,Ca,Fe2+)Mn(Mg,Fe2+,Fe3+)3(PO4)3Mon.
8.AC.10NickenichiteNa0.8Ca0.4Cu0.4(Mg,Fe)3(AsO4)3Mon. 2/m : B2/b
8.AC.10VaruliteNaCaMn2+Mn2+2(PO4)3Mon. 2/m : B2/b
8.AC.10FerrohagendorfiteNaCaFe2+Fe2+2(PO4)3Mon.
8.AC.10BradaczekiteNaCu4(AsO4)3Mon. 2/m : B2/b
8.AC.10YazganiteNaFe3+2(Mg,Mn2+)(AsO4)3 · H2OMon. 2/m : B2/b
8.AC.10GroatiteNaCaMn2(PO4)(HPO4)2Mon. 2/m : B2/b
8.AC.15BobfergusoniteNa2Mn5FeAl(PO4)6Mon. 2/m : P2/b
8.AC.15Ferrowyllieite(Na,Ca,Mn)(Fe,Mn)(Fe,Fe,Mg)Al(PO4)3Mon. 2/m : P21/b
8.AC.15QingheiiteNaMn3+Mg(Al,Fe3+)(PO4)3Mon. 2/m : P21/b
8.AC.15Rosemaryite(Na,Ca,Mn)(Mn,Fe2+)(Fe3+,Mg)Al(PO4)3Mon. 2/m : P21/b
8.AC.15Wyllieite(Na,Ca,Mn)(Mn,Fe)(Fe,Mg)Al(PO4)3Mon. 2/m
8.AC.15Ferrorosemaryite◻NaFe2+Fe3+Al(PO4)3Mon.
8.AC.15Qingheiite-(Fe2+)Na2Fe2+MgAl(PO4)3Mon. 2/m : P21/m
8.AC.18ManitobaiteNa16Mn2+ 25Al8(PO4)30Mon. m : Pb
8.AC.20MarićiteNaFe2+(PO4)Orth. mmm (2/m 2/m 2/m) : Pmna
8.AC.25Berzeliite(NaCa2)Mg2(AsO4)3Iso. m3m (4/m 3 2/m) : Ia3d
8.AC.25ManganberzeliiteNaCa2Mn2+2(AsO4)3Iso. m3m (4/m 3 2/m) : Ia3d
8.AC.25Palenzonaite(Ca,Na)3CaMn2+2(VO4)3Iso. m3m (4/m 3 2/m) : Ia3d
8.AC.25SchäferiteCa2NaMg2(VO4)3Iso.
8.AC.30BrianiteNa2CaMg(PO4)2Mon. 2/m : P21/b
8.AC.35Vitusite-(Ce)Na3(Ce,La,Nd)(PO4)2Orth. mm2 : Pca21
8.AC.40Olgite(Sr,Ba)(Na,Sr,REE)2Na(PO4)2Trig. 3m (3 2/m) : P3m1
8.AC.40Bario-olgite(Ba,Sr)(Na,Sr,REE)2Na(PO4)2 · Trig. 3 : P3
8.AC.45StrontiowhitlockiteSr9Mg(PO4)6(HPO4)Trig. 3m : R3c
8.AC.45WhitlockiteCa9Mg(PO4)6(HPO4)Trig. 3m : R3c
8.AC.45MerrilliteCa9NaMg(PO4)7Trig. 3m : R3m
8.AC.45TuiteCa3(PO4)2Trig. 3m (3 2/m) : R3m
8.AC.45FerromerrilliteCa9NaFe2+(PO4)7Trig. 3m : R3c
8.AC.50Chladniite{Ca}{Na8}{Ca4Na4}{(Mg,Fe2+)43}(PO4)36Trig. 3 : R3
8.AC.50Fillowite{Mn2+}{Na8}{Ca4Na4}{(Mn2+,Fe2+)43}(PO4)36Trig. 3 : R3
8.AC.50JohnsomervilleiteNa10Ca6Mg18Fe25(PO4)36Trig.
8.AC.50Galileiite{Fe2+}{Na8}{Fe2+4Na4}{Fe2+43}(PO4)36Trig. 3 : R3
8.AC.50Stornesite-(Y){(Y, Ca)}{Na62}{(Ca,Na)8}{(Mg,Fe2+)43}(PO4)36Trig. 3 : R3
8.AC.50XenophylliteNa4Fe2+7(PO4)6Tric. 1 : P1
8.AC.55HarrisoniteCa(Fe2+,Mg)6(PO4)2(SiO4)2Trig.
8.AC.60KosnariteKZr2(PO4)3Trig. 3m (3 2/m) : R3c
8.AC.65Panethite(Na,Ca)2(Mg,Fe2+)2(PO4)2Mon. 2/m : P21/b
8.AC.70StanfielditeCa4Mg5(PO4)6Mon.
8.AC.75RonneburgiteK2MnV4O12Mon. 2/m
8.AC.80Tillmannsite(Ag3Hg)(VO4,AsO4)Tet. 4 : I4
8.AC.85FilatoviteK(Al,Zn)2(As,Si)2O8Mon. 2/m

Related Minerals - Dana Grouping (8th Ed.)Hide

38.3.4.1WhitlockiteCa9Mg(PO4)6(HPO4)Trig. 3m : R3c
38.3.4.2StrontiowhitlockiteSr9Mg(PO4)6(HPO4)Trig. 3m : R3c
38.3.4.3Merrillite-(Ca)(Ca,◻)19Mg2(PO4)14Trig.
38.3.4.4MerrilliteCa9NaMg(PO4)7Trig. 3m : R3m
38.3.4.6TuiteCa3(PO4)2Trig. 3m (3 2/m) : R3m
38.3.4.7FerromerrilliteCa9NaFe2+(PO4)7Trig. 3m : R3c

Other InformationHide

Notes:
Insoluble in water, acetone, or hydrochloric acid.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for BobdownsiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Gnos, E., et al. (2002): Sayh al Uhaymir 094: a new martian meteorite from the Oman desert: Meteoritics & Planetary Science 37, 835-854.
Tait, K.T., Barkley, M.C., Thompson, R.M., Origlieri, M.J., Evans, S.H., Prewitt, C.T. & Yang, H. (2011): Bobdownsite, a new mineral species from Big Fish River, Yukon, Canada, and its structural relationship with whitlockite-type compounds. Canadian Mineralogist, 49, 1065-1078.
CNMNC Newsletter No. 41, February 2018, page 184; European Journal of Mineralogy: 30: 183-186.

Internet Links for BobdownsiteHide

Localities for BobdownsiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Canada (FRL)
 
  • Yukon
    • Dawson mining district
TAIT, K.T., BARKLEY, M.C., THOMPSON, R.M., ORIGLIER, M.J., EVANS, S.H., PREWITT, C.T. & YANG, H. (2011) Bobdownsite, a new mineral species from Big Fish River, Yukon, Canada, and its structural relationship with whitlockite-type compounds. Canadian Mineralogist, 49, 1065-1078.
Tait, K.T., Barkley, M.C., Thompson, R.M., Origlieri, M.J., Evans, S.H., Prewitt, C.T. & Yang, H. (2011): Bobdownsite, a new mineral species from Big Fish River, Yukon, Canada, and its structural relationship with whitlockite-type compounds. Canadian Mineralogist, 49, 1065-1078.
Oman
 
  • Al Wusta Region
    • Sayh al Uhaymir
MPS 37,835(2002)
USA
 
  • South Dakota
    • Custer Co.
      • Custer District
        • Fourmile
TAIT, K.T., BARKLEY, M.C., THOMPSON, R.M., ORIGLIERI, M.J., EVANS, S.H., PREWITT, C.T. & YANG, H. (2011) Bobdownsite, a new mineral species from Big Fish River, Yukon, Canada, and its structural relationship with whitlockite-type compounds. Canadian Mineralogist, 49, 1065-1078.
Mineral and/or Locality  
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