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Welshite

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Långban, Filipstad, Värmland, Sweden
© Knut Eldjarn

Show Welshite Photos (5)



Formula:
Ca
 
4
Mg
 
9
Sb
 
3
O
 
4
[Si
 
6
Be
 
3
AlFe
 
2
O
 
36
]
System:TriclinicColour:Reddish black, reddish ...
Hardness:6
Member of:Rhönite Group > Sapphirine Supergroup
Name:
Named after Wilfred R. Welsh (1915-2006), 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:
SwedenborgiteRoméite GroupRichteritePhlogopiteHausmannite
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:Al, 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

Member of:Rhönite Group > Sapphirine Supergroup
Other Members of Group:

- +
Dorrite
Ca
 
2
(Mg,Fe
2+
 
)
 
2
Fe
3+
4
[O
 
2
|Al
 
4
Si
 
2
O
 
18
]
Høgtuvaite
(Ca,Na)
 
2
(Fe
2+
 
,Fe
3+
 
,Ti)
 
6
[O
 
2
|Be(Si,Al)
 
5
O
 
18
]
Leucorhönite
Ca
 
2
(Mg,Fe
3+
 
,Al)
 
6
(Si,Al)
 
6
O
 
20
Makarochkinite
Ca
 
2
Fe
2+
4
Fe
3+
 
Ti[O
 
2
|BeAlSi
 
4
O
 
18
]
Rhönite
Ca
 
2
(Mg,Fe
2+
 
,Fe
3+
 
,Ti)
 
6
[O
 
2
|(Si,Al)
 
6
O
 
18
]
Serendibite
(Ca,Na)
 
2
(Mg,Fe
2+
 
)
 
3
(Al,Fe
3+
 
)
 
3
[O
 
2
|(Si,Al,B)
 
6
O
 
18
]
Related Minerals - Nickel-Strunz Grouping):

- +
9.DH.05Leucophanite
NaCaBeSi
 
2
O
 
6
F
9.DH.10Ohmilite
Sr
 
3
(Ti,Fe
3+
 
)(Si
 
4
O
 
12
)(O,OH) · 2-3H
 
2
O
9.DH.15Haradaite
SrVSi
 
2
O
 
7
9.DH.15Suzukiite
BaVSi
 
2
O
 
7
9.DH.20Batisite
BaNaNaTi
 
2
(Si
 
4
O
 
12
)O
 
2
9.DH.20Shcherbakovite
(K,Ba)KNa(Ti,Nb)
 
2
(Si
 
4
O
 
12
)O
 
2
9.DH.25Taikanite
Sr
 
3
BaMn
2+
2
(Si
 
4
O
 
12
)O
 
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
Ti(Si
 
6
O
 
18
)O
 
2
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
(Si
 
6
O
 
18
)O
 
2
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
(Si
 
6
O
 
18
)O
 
2
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
 
17
]O
 
3
(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
Si
 
4
O
 
10
F
Related Minerals - Hey's Index Grouping:

- +
17.7.1Suzukiite
BaVSi
 
2
O
 
7
17.7.2Franciscanite
Mn
2+
6
(V
5+
 
,☐)
 
2
(SiO
 
4
)
 
2
(O,OH)
 
6
17.7.3Kurumsakite
(Zn,Ni,Cu)
 
8
Al
 
8
V
5+
2
Si
 
5
O
 
35
 · 27H
 
2
O (?)
17.7.4Ardennite-(As)
Mn
2+
4
(Al,Mg)
 
6
(Si
 
3
O
 
10
)(SiO
 
4
)
 
2
(AsO
 
4
,VO
 
4
)(OH)
 
6
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
2+
4
(HAsSi
 
3
O
 
13
)
17.7.8Dixenite
CuMn
2+
14
Fe
2+
 
(SiO
 
4
)
 
2
(As
5+
 
O
 
4
)(As
3+
 
O
 
3
)
 
5
(OH)
 
6
17.7.9Asbecasite
Ca
 
3
(Ti,Sn
4+
 
)Be
 
2
(AsO
 
3
)
 
6
(SiO
 
4
)
 
2
17.7.10Mcgovernite
Mn
 
19
Zn
 
3
(AsO
 
4
)
 
3
(AsO
 
3
)(SiO
 
4
)
 
3
(OH)
 
21
17.7.11Kraisslite
(Mn
2+
 
,Mg)
 
24
Zn
 
4
(SiO
 
4
)
 
8
(AsO
 
4
)
 
4
(OH)
 
12
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
(AsO
 
4
)
 
2
(SiO
 
4
)
 
2
(OH)
 
8
17.7.15Yeatmanite
Zn
 
6
Mn
2+
9
Sb
5+
2
(SiO
 
4
)
 
4
O
 
12
17.7.17Katoptrite
(Mn
2+
 
,Mg)
 
13
(Al,Fe
3+
 
)
 
4
Sb
5+
2
(SiO
 
4
)
 
2
O
 
20
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+
 
(SiO
 
4
)
 
2
O
 
16
17.7.20Chapmanite
Fe
3+
2
Sb
3+
 
(SiO
 
4
)
 
2
(OH)
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
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    • Localities for Welshite

    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.
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    (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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