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Welshite

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Långban, Filipstad, Värmland, Sweden
© Knut Eldjarn

Show Welshite Photos (3)
Formula:
Ca
 
4
Mg
 
9
Sb
 
3
O
 
4
[Si
 
6
Be
 
3
AlFe
 
2
O
 
36
]
System:TriclinicColour:Reddish black, reddish ...
Hardness:6
Name:Named after Wilfred R. Welsh, science teacher, auxillary 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 collection now reside. This species was named in his honor by one of his former students: Dr. Paul Moore.


Aenigmatite Group.

The only non-centrosymmetric member of the sapphirine group.

Classification of Welshite

IMA status:Approved 1973
Strunz 8th edition ID:8/F.14-70
Nickel-Strunz 10th (pending) edition ID:9.DH.40

9 : SILICATES (Germanates)
D : Inosilicates
H : Inosilicates with 4-periodic single chains, Si4O12
Dana 8th edition ID:69.2.1a.7

69 : INOSILICATES Chains with Side Branches or Loops
2 : Chains with Side Branches or Loops with P>2
Hey's CIM Ref.:17.7.16

17 : Silicates Containing other Anions
7 : Silicates with vanadate, arsenate or antimonate
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Type Occurrence of Welshite

Type Locality:Långban, Filipstad, Värmland, Sweden
Place of Conservation of Type Material:U.S. National Museum of Natural History, Smithsonian Institution, Washington, D.C., USA
Year of Discovery:1978
Geological Setting of type material:Hematitic-dolomitic skarn
Associated Minerals at type locality:
SwedenborgiteRoméiteRichteritePhlogopiteHausmannite
BerzeliiteAdelite

Physical Properties of Welshite

Lustre:Sub-Adamantine
Diaphaneity (Transparency):Transparent, Translucent
Colour:Reddish black, reddish brown. brown-black; Brownish orange in transmitted light
Streak:Pale brown
Hardness (Mohs):6
Cleavage:None Observed
Fracture:Conchoidal
Density (measured):3.77 g/cm3
Density (calculated):3.71 g/cm3

Crystallography of Welshite

Crystal System:Triclinic
Class (H-M):1 - Pedial
Space Group: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 Volume:V 738.8 ų
Z:1
Morphology:Pseudomonoclinic. Crystals stout prismatic [001]. May be flattened on {010}.
Twinning:Polysynthetic on {010}.

Optical Data of Welshite

Type:Biaxial (+)
RI values: nα = 1.810 nβ = 1.830
2V:Measured: 45°
Maximum Birefringence:δ = 1.810

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Very High
Dispersion:r > v

Chemical Properties of Welshite

Formula:
Ca
 
4
Mg
 
9
Sb
 
3
O
 
4
[Si
 
6
Be
 
3
AlFe
 
2
O
 
36
]
Essential elements:Be, Ca, Fe, Mg, O, Sb, Si
All elements listed in formula:Al, Be, Ca, Fe, Mg, O, Sb, Si
Common Impurities:Al,As,Mn,Be

Relationship of Welshite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.DH.05Leucophanite
NaCaBeSi
 
2
O
 
6
F
9.DH.10Ohmilite
Sr
 
3
(Ti,Fe
3+
 
)[(O,OH)|(Si
 
2
O
 
6
)
 
2
] · 2-3H
 
2
O
9.DH.15Haradaite
SrVSi
 
2
O
 
7
9.DH.15Suzukiite
BaVSi
 
2
O
 
7
9.DH.20Batisite
Na
 
2
BaTi
 
2
[O|Si
 
2
O
 
6
]
 
2
9.DH.20Shcherbakovite
Na(K,Ba)
 
2
(Ti,Nb)
 
2
[O|Si
 
2
O
 
6
]
 
2
9.DH.25Taikanite
Sr
 
3
BaMn
2+
2
[O|Si
 
2
O
 
6
]
 
2
9.DH.30Krauskopfite
BaSi
 
2
O
 
5
·3H
 
2
O
9.DH.35Balangeroite
(Mg,Fe,Fe,Mn)
 
42
Si
 
16
O
 
54
(OH)
 
40
9.DH.35Gageite
Mn
 
21
O
 
3
(Si
 
4
O
 
12
)
 
2
(OH)
 
20
9.DH.40Aenigmatite
Na
 
2
Fe
2+
5
TiO
 
2
(Si
 
6
O
 
18
)
9.DH.40Dorrite
Ca
 
2
(Mg,Fe
2+
 
)
 
2
Fe
3+
4
[O
 
2
|Al
 
4
Si
 
2
O
 
18
]
9.DH.40Høgtuvaite
(Ca,Na)
 
2
(Fe
2+
 
,Fe
3+
 
,Ti)
 
6
[O
 
2
|Be(Si,Al)
 
5
O
 
18
]
9.DH.40Krinovite
Na
 
2
Mg
 
4
Cr
3+
2
[O
 
2
|Si
 
6
O
 
18
]
9.DH.40Makarochkinite
Ca
 
2
Fe
2+
4
Fe
3+
 
Ti[O
 
2
|BeAlSi
 
4
O
 
18
]
9.DH.40Rhönite
Ca
 
2
(Mg,Fe
2+
 
,Fe
3+
 
,Ti)
 
6
[O
 
2
|(Si,Al)
 
6
O
 
18
]
9.DH.40Serendibite
(Ca,Na)
 
2
(Mg,Fe
2+
 
)
 
3
(Al,Fe
3+
 
)
 
3
[O
 
2
|(Si,Al,B)
 
6
O
 
18
]
9.DH.40Wilkinsonite
Na
 
2
Fe
2+
4
Fe
3+
2
[O
 
2
|Si
 
6
O
 
18
]
9.DH.45Sapphirine
(Mg,Fe)
 
4-x
Al
 
4+x
[Al
 
4+x
Si
 
2-x
O
 
18
]O
 
2
9.DH.50Khmaralite
(Mg,Al,Fe)
 
16
[(Al,Si,Be)
 
12
O
 
36
]O
 
4
9.DH.55Surinamite
(Mg,Fe)
 
3
Al
 
4
BeSi
 
3
O
 
16
9.DH.60Deerite
(Fe,Mn)
 
6
(Fe,Al)
 
3
Si
 
6
O
 
20
(OH)
 
5
9.DH.65Howieite
Na(Fe,Mn)
 
10
(Fe,Al)
 
2
Si
 
12
O
 
31
(OH)
 
13
9.DH.65Taneyamalite
(Na,Ca)(Mn,Mg,Fe)
 
12
Si
 
12
(O,OH)
 
44
9.DH.70Johninnesite
Na
 
2
Mn
2+
9
Mg
 
7
(OH)
 
8
[AsO
 
4
]
 
2
[Si
 
6
O
 
17
]
 
2
9.DH.75Agrellite
NaCa
 
2
[F|Si
 
4
O
 
10
]
Related Minerals - Hey's Index Grouping:

- +
17.7.1Suzukiite
BaVSi
 
2
O
 
7
17.7.2Franciscanite
Mn
2+
6
(V
5+
 
,[])
 
2
[(O,OH)
 
3
|SiO
 
4
]
 
2
17.7.3Kurumsakite
(Zn,Ni,Cu)
 
8
Al
 
8
V
 
2
Si
 
5
O
 
35
·27H
 
2
O (or near)
17.7.4Ardennite-(As)
Mn
2+
4
[(Al,Mg)
 
6
][(OH)
 
6
|(AsO
 
4
,VO
 
4
)|(SiO
 
4
)
 
2
|Si
 
3
O
 
10
]
17.7.5Medaite
(Mn,Ca)
 
6
(V,As)Si
 
5
O
 
18
OH
17.7.6Johninnesite
Na
 
2
Mn
2+
9
Mg
 
7
(OH)
 
8
[AsO
 
4
]
 
2
[Si
 
6
O
 
17
]
 
2
17.7.7Tiragalloite
Mn
 
4
AsSi
 
3
O
 
12
(OH)
17.7.8Dixenite
CuMn
2+
14
Fe
2+
 
[(OH)
 
6
|(AsO
 
3
)
 
5
|AsO
 
4
|(SiO
 
4
)
 
2
]
17.7.9Asbecasite
Ca
 
3
(Ti,Sn
4+
 
)Be
 
2
[(AsO
 
3
)
 
3
|SiO
 
4
]
 
2
17.7.10Mcgovernite
(Mn,Mg,Zn)
 
273
As
3+
~12
As
5+
~30
Si
 
~42
O
 
324
(OH)
 
252
17.7.11Kraisslite
(Mn
2+
 
,Mg)
 
24
Zn
 
4
[(OH)
 
12
|(AsO
 
4
)
 
4
|(SiO
 
4
)
 
8
]
17.7.12Schallerite
(Mn,Fe)
 
16
Si
 
12
As
 
3
O
 
36
(OH)
 
17
17.7.13Nelenite
(Mn,Fe)
 
16
(Si
 
12
O
 
30
)(OH)
 
14
[As
3+
3
O
 
6
(OH)
 
3
]
17.7.14Kolicite
Mn
2+
7
Zn
 
4
[(OH)
 
8
|(AsO
 
4
)
 
2
|(SiO
 
4
)
 
2
]
17.7.15Yeatmanite
Mn
2+
7
Zn
 
8
Sb
5+
2
[O
 
3
|SiO
 
4
]
 
4
17.7.17Katoptrite
(Mn
2+
 
,Mg)
 
13
(Al,Fe
3+
 
)
 
4
Sb
5+
2
[O
 
10
|SiO
 
4
]
 
2
17.7.18Parwelite
Mn
 
10
Sb
 
2
As
 
2
Si
 
2
O
 
24
17.7.19Långbanite
(Mn
2+
 
,Ca)
 
4
(Mn
3+
 
,Fe
3+
 
)
 
9
Sb
5+
 
[O
 
8
|SiO
 
4
]
 
2
17.7.20Chapmanite
Fe
3+
2
Sb
3+
 
[OH|(SiO
 
4
)
 
2
]
17.7.21Cervandonite-(Ce)
(Ce,Nd,La)(Fe
3+
 
,Fe
2+
 
,Ti,Al)
 
3
O
 
2
(Si
 
2
O
 
7
)(As
3+
 
O
 
3
)(OH)

Other Names for Welshite

Synonyms:
IMA1973-019
Other Languages:
German:Welshit
Spanish:Welshita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Welshite

Reference List: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": Am. Min. 92, 80-90.

Internet Links for Welshite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
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  • Welshite details from Handbook of Mineralogy (PDF)
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    Localities for Welshite

    Hide Locality List
    The 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.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Sweden
     
    • Värmland
      • Filipstad
    		Min.Mag.(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.
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