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Welshite

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Wilfred R. Welsh
Formula:
Ca4Mg9Sb3O4[Si6Be3AlFe2O36]
Colour:
Reddish black, reddish brown. brown-black; Brownish orange in transmitted light
Lustre:
Sub-Adamantine, Resinous
Hardness:
6
Specific Gravity:
3.77
Crystal System:
Triclinic
Name:
Named in 1970 and formally described in 1978 by Paul (Paulus) Brian Moore in honor of Wilfred "Bill" Reinhardt Welsh [January 29, 1915 West Orange, New Jersey, USA - November 14, 2002 Newton, New Jersey, USA), public school science teacher, auxiliary police officer, motorcycle enthusiast, and amateur mineralogist of Upper Saddle River, New Jersey (USA). He was past President of the Franklin Mineral Museum and a significant benefactor to that institution, where his mineral and fossil collections now reside. Dr. Paul Moore was a student of Bill's and the naming acknowledged an extraordinary mentor whose verve inspired Paul to become a mineralogist.
Isostructural with:
Aenigmatite Group.

The only non-centrosymmetric member of the sapphirine group.


Hide all sections | Show all sections

Classification of WelshiteHide

Approved
Approval Year:
1973
9.DH.40

9 : SILICATES (Germanates)
D : Inosilicates
H : Inosilicates with 4-periodic single chains, Si4O12
69.2.1a.7

69 : INOSILICATES Chains with Side Branches or Loops
2 : Chains with Side Branches or Loops with P>2
17.7.16

17 : Silicates Containing other Anions
7 : Silicates with vanadate, arsenate or antimonate

Physical Properties of WelshiteHide

Sub-Adamantine, Resinous
Transparency:
Transparent, Translucent
Colour:
Reddish black, reddish brown. brown-black; Brownish orange in transmitted light
Streak:
Pale brown
Hardness:
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
3.77 g/cm3 (Measured)    3.71 g/cm3 (Calculated)

Optical Data of WelshiteHide

Type:
Biaxial (+)
RI values:
nα = 1.811 nγ = 1.831
Warning: number_format() expects parameter 1 to be float, string given in /home/mindat/www/show_class.php on line 3772
2V:
Measured: 45°
Birefringence:
0.020
Max Birefringence:
δ = 0.020
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v
Pleochroism:
Not Visible

Chemical Properties of WelshiteHide

Formula:
Ca4Mg9Sb3O4[Si6Be3AlFe2O36]
IMA Formula:
Ca4(Mg9Sb5+3)O4[Si6Be3AlFe3+2O36]
Common Impurities:
Al,As,Mn,Be

Crystallography of WelshiteHide

Crystal System:
Triclinic
Class (H-M):
1 - Pedial
Space Group:
P1
Setting:
P1
Cell Parameters:
a = 10.394(3) Å, b = 10.777(3) Å, c = 8.896(2) Å
α = 105.953°, β = 96.294°, γ = 124.948°
Ratio:
a:b:c = 0.964 : 1 : 0.825
Unit Cell V:
738.8 ų
Z:
1
Morphology:
Pseudomonoclinic. Crystals stout prismatic [001]. May be flattened on {010}. Free-standing crystals are rare.
Twinning:
Polysynthetic on {010}.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
7.32 (70)
4.73 (60)
2.910 (70)
2.670 (60)
2.530 (100)
1.489 (70)
1.460 (70)

Type Occurrence of WelshiteHide

Place of Conservation of Type Material:
U.S. National Museum of Natural History, Smithsonian Institution, Washington, D.C., USA
Geological Setting of Type Material:
Hematitic-dolomitic skarn
Associated Minerals at Type Locality:

Synonyms of WelshiteHide

Other Language Names for WelshiteHide

German:Welshit
Spanish:Welshita

Relationship of Welshite to other SpeciesHide

Other Members of this group:
DorriteCa4(Mg3Fe3+9)O4(Si3Al8Fe3+O36)Tric.
HøgtuvaiteCa4[Fe2+6Fe3+6]O4[Si8Be2Al2O36]Tric. 1 : P1
LeucorhöniteCa2(Mg,Fe3+,Al)6(Si,Al)6O20Tric.
Makarochkinite(Ca,Na)2Fe2+4Fe3+Ti[O2|BeAlSi4O18]Tric. 1 : P1
RhöniteCa2(Mg,Fe2+,Fe3+,Ti)6[O2|(Si,Al)6O18]Tric. 1 : P1
SerendibiteCa4[Mg6Al6]O4[Si6B3Al3O36]Tric. 1 : P1

Common AssociatesHide

Associated Minerals Based on Photo Data:
Calcite2 photos of Welshite associated with Calcite on mindat.org.
Roméite Group1 photo of Welshite associated with Roméite Group on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.DH.05LeucophaniteNaCaBeSi2O6FOrth. 2 2 2 : P21 21 21
9.DH.10OhmiliteSr3(Ti,Fe3+)(Si4O12)(O,OH) · 2-3H2OMon.
9.DH.15HaradaiteSrVSi2O7Orth.
9.DH.15SuzukiiteBaVSi2O7Orth.
9.DH.20BatisiteBaNaNaTi2(Si4O12)O2Orth.
9.DH.20Shcherbakovite(K,Ba)KNa(Ti,Nb)2(Si4O12)O2Orth.
9.DH.25TaikaniteSr3BaMn2+2(Si4O12)O2Mon.
9.DH.30KrauskopfiteBaSi2O5 · 3H2OMon.
9.DH.35Balangeroite(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)40Mon.
9.DH.35GageiteMn21(Si4O12)2O3(OH)20Mon. 2/m
9.DH.40AenigmatiteNa2Fe2+5Ti(Si6O18)O2Tric. 1 : P1
9.DH.40DorriteCa4(Mg3Fe3+9)O4(Si3Al8Fe3+O36)Tric.
9.DH.40HøgtuvaiteCa4[Fe2+6Fe3+6]O4[Si8Be2Al2O36]Tric. 1 : P1
9.DH.40KrinoviteNa2Mg4Cr3+2(Si6O18)O2Tric.
9.DH.40Makarochkinite(Ca,Na)2Fe2+4Fe3+Ti[O2|BeAlSi4O18]Tric. 1 : P1
9.DH.40RhöniteCa2(Mg,Fe2+,Fe3+,Ti)6[O2|(Si,Al)6O18]Tric. 1 : P1
9.DH.40SerendibiteCa4[Mg6Al6]O4[Si6B3Al3O36]Tric. 1 : P1
9.DH.40WilkinsoniteNa2Fe2+4Fe3+2(Si6O18)O2Tric. 1 : P1
9.DH.45SapphirineMg4(Mg3Al9)O4[Si3Al9O36]Mon. 2/m : P21/b
9.DH.50Khmaralite(Mg,Al,Fe)16[(Al,Si,Be)12O36]O4Mon. 2/m : P21/b
9.DH.55Surinamite(Mg,Fe)3Al4BeSi3O16Mon.
9.DH.60Deerite(Fe,Mn)6(Fe,Al)3[Si6O17]O3(OH)5Mon.
9.DH.65HowieiteNa(Fe,Mn)10(Fe,Al)2Si12O31(OH)13Tric.
9.DH.65Taneyamalite(Na,Ca)(Mn,Mg,Fe)12Si12(O,OH)44Tric.
9.DH.70JohninnesiteNa2Mn2+9Mg7(OH)8[AsO4]2[Si6O17]2Tric.
9.DH.75AgrelliteNaCa2Si4O10FTric.

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

69.2.1a.1AenigmatiteNa2Fe2+5Ti(Si6O18)O2Tric. 1 : P1
69.2.1a.2DorriteCa4(Mg3Fe3+9)O4(Si3Al8Fe3+O36)Tric.
69.2.1a.3HøgtuvaiteCa4[Fe2+6Fe3+6]O4[Si8Be2Al2O36]Tric. 1 : P1
69.2.1a.4KrinoviteNa2Mg4Cr3+2(Si6O18)O2Tric.
69.2.1a.5RhöniteCa2(Mg,Fe2+,Fe3+,Ti)6[O2|(Si,Al)6O18]Tric. 1 : P1
69.2.1a.6SerendibiteCa4[Mg6Al6]O4[Si6B3Al3O36]Tric. 1 : P1
69.2.1a.8WilkinsoniteNa2Fe2+4Fe3+2(Si6O18)O2Tric. 1 : P1

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

17.7.1SuzukiiteBaVSi2O7Orth.
17.7.2FranciscaniteMn2+6(V5+,☐)2(SiO4)2(O,OH)6Hex.
17.7.3Kurumsakite(Zn,Ni,Cu)8Al8V5+2Si5O35 · 27H2O (?)
17.7.4Ardennite-(As)Mn2+4Al4(AlMg)(AsO4)(SiO4)2(Si3O10)(OH)6Orth. mmm (2/m 2/m 2/m)
17.7.5MedaiteMn2+6V5+Si5O18(OH)Mon.
17.7.6JohninnesiteNa2Mn2+9Mg7(OH)8[AsO4]2[Si6O17]2Tric.
17.7.7TiragalloiteMn2+4As5+Si3O12(OH)Mon. 2/m
17.7.8DixeniteCuMn2+14Fe2+(SiO4)2(As5+O4)(As3+O3)5(OH)6Trig.
17.7.9AsbecasiteCa3(Ti,Sn4+)Be2(AsO3)6(SiO4)2Trig. 3m : P3c1
17.7.10McgoverniteMn19Zn3(AsO4)3(AsO3)(SiO4)3(OH)21Trig. 3m (3 2/m)
17.7.11KraissliteZn3(Mn,Mg)25(Fe3+,Al)(As3+O3)2[(Si,As5+)O4]10(OH)16Orth. 2 2 2 : C2 2 21
17.7.12SchalleriteMn2+16As3Si12O36(OH)17Trig. 3m : P3m1
17.7.13Nelenite(Mn,Fe)16(Si12O30)(OH)14[As3+3O6(OH)3]Mon.
17.7.14KoliciteMn2+7Zn4(AsO4)2(SiO4)2(OH)8Orth. mmm (2/m 2/m 2/m) : Cmca
17.7.15YeatmaniteZn6Mn2+9Sb5+2(SiO4)4O12Tric.
17.7.17Katoptrite(Mn2+,Mg)13(Al,Fe3+)4Sb5+2(SiO4)2O20Mon. 2/m : B2/m
17.7.18ParweliteMn10Sb2As2Si2O24Mon. m : Bb
17.7.19LångbaniteMn2+4Mn3+9Sb5+O16(SiO4)2Trig. 3m : P3m1
17.7.20ChapmaniteFe3+2Sb3+(Si2O5)O3(OH)Mon. m : Bm
17.7.21Cervandonite-(Ce)(Ce,Nd,La)(Fe3+,Fe2+,Ti,Al)3O2(Si2O7)(As3+O3)(OH)Trig. 3m : R3m

Fluorescence of WelshiteHide

Not fluorescent in UV

Other InformationHide

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 WelshiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Moore, Paul B. (1970) Mineralogy and Chemistry of Langban-type Deposits in Bergslagen, Sweden, Mineralogical Record, 1: 154-172.
Moore, P. B. (1978) Welshite, Ca2Mg4Fe 3+Sb 5+O2[Si4Be2O18], A New Member of the Aenignatite Group. Mineralogical Magazine: 42: 129-132.
American Mineralogist (1979): 64: 244 (abstract).
Canadian Mneralogist (1994): 32: 439.
Grew, E.S., et al.(2007): "The crystal chemistry of welshite, a non-centrosymmetric (P1) aenigmatite-sapphirine-surinamite group mineral": American Mineralogist, 92, 80-90.

Internet Links for WelshiteHide

Localities for WelshiteHide

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.
Sweden (TL)
 
  • Värmland
    • Filipstad
Mineralogical Magazine(1978) 42, 129-132; Nysten, P., Holtstam, D. and Jonsson, E. (1999) The Långban minerals. In Långban - The mines,their minerals, geology and explorers (D. Holtstam and J. Langhof, eds.), Swedish Museum of Natural History and Raster Förlag, Stockholm & Chr. Weise Verlag, Munich, pp. 89-183.
Mineral and/or Locality  
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