Welshite Mineral Data

General Welshite Information

Chemical Formula:

Ca4Mg9Sb3O4[Si6Be3AlFe2O36]

Composition:

Molecular Weight = 1,746.53 gm

Calcium 8.74 % Ca 12.23 % CaO

Magnesium 10.91 % Mg 18.09 % MgO

Manganese 3.68 % Mn 4.75 % MnO

Beryllium 1.67 % Be 4.64 % BeO

Aluminum 2.38 % Al 4.50 % Al₂O₃

Zinc 0.15 % Zn 0.19 % ZnO

Iron 4.16 % Fe 0.21 % FeO / 5.71 % Fe₂O₃

Silicon 8.96 % Si 19.16 % SiO₂

Antimony 21.12 % Sb 28.06 % Sb₂O₅

Arsenic 1.59 % As 2.43 % As₂O₅

Oxygen 36.64 % O

______ ______

100.00 % 99.98 % = TOTAL OXIDE

Empirical Formula:

Be_3.24

IMA Status:

Approved IMA 1978

Locality:

Langban, Varmland, Sweden. Link to MinDat.org Location Data.

Name Origin:

Named for Wilfred R. Welsh (1915-?), amateur mineralogist and teacher of natural sciences.

Name Pronunciation:

Welshite

Welshite Image

Images:

Welshite

Comments: Deep red, prismatic crystal of welshite in matrix.
Location: Langban, Varmland, Sweden. Scale: Crystal size 1.5 mm.
© Tom Loomis / Dakota Matrix

Welshite Crystallography

Axial Ratios:

a:b:c =0.9644:1:0.8254

Cell Dimensions:

a = 10.394, b = 10.777, c = 8.896, Z = 1; alpha = 105.953°, beta = 96.294°, gamma = 124.948° V = 780.61 Den(Calc)= 3.72

Crystal System:

Triclinic - PedialH-M Symbol (1) Space Group: P1

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.53(1), 2.91(0.7), 7.324(0.7),

Crystal Structure:

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Grew E S , Barbier J , Britten J , Halenius U , Shearer C K , American Mineralogist , 92 (2007) p.80-90, The crystal chemistry of welshite, a non-centrosymmetric (P1) aenigmatite-, sapphirine-surinamite group mineral

Physical Properties of Welshite

Cleavage:

None

Color:

Brown, Reddish black, Orange brown, Deep tan.

Density:

3.77

Diaphaneity:

Subtranslucent to Opaque

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

6 - Orthoclase

Luster:

Subadamantine

Streak:

light brown

Optical Properties of Welshite

Gladstone-Dale:

CI meas= -0.099 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.057 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2083,KPDmeas= 0.2166,KC= 0.1971
Ncalc = 1.74 - 1.77

Optical Data:

Biaxial (+/-), a=1.81, b=1.81, g=1.83, bire=0.0200, 2V(Calc)=0, 2V(Meas)=45.

Pleochroism (x):

none.

Pleochroism (y):

none.

Pleochroism (z):

nnone.

Calculated Properties of Welshite

Electron Density:

Bulk Density (Electron Density)=3.74 gm/cc
note: Specific Gravity of Welshite =3.92 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_Welshite= 70.38 barns/electron
U=PE_Welshite x rElectron Density= 262.93 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Welshite is Not Radioactive

Welshite Classification

Dana Class:

69.02.01a.07 (69)Inosilicate Chains with Side Branches or Loops

(69.02)with P>2

(69.02.01a)Aenigmatite and related species (Aenigmatite subgroup)

69.02.01a.01 Aenigmatite (Na,Ca)4(Fe,Ti,Mg)12Si12O40 P1 1

69.02.01a.02 Dorrite Ca2Mg2Fe4(Al,Fe)4Si2O20 P1,P 1 Tri

69.02.01a.03 Hogtuvaite (Ca,Na)2(Fe,Fe,Ti,Mg,Mn)6(Si,Be,Al)6O20 P1 1

69.02.01a.04 Krinovite NaMg2CrSi3O10 P1 1

69.02.01a.05 Rhonite Ca2(Mg,Fe,Fe,Ti)6(Si,Al)6O20 P1 1

69.02.01a.06 Serendibite Ca2(Mg,Al)6(Si,Al,B)6O20 P1 1

69.02.01a.07 Welshite Ca4Mg9Sb3O4[Si6Be3AlFe2O36] P1 1

69.02.01a.08 Wilkinsonite Na2Fe4Fe2Si6O20 P1 1

69.02.01a.09 Makarochkinite! Ca2Fe4FeTiSi4BeAlO20 P1 1

Strunz Class:

09.DH.45 09 - SILICATES (Germanates)

09.D - Inosilicates* Structural terminology according to Liebau (1985)

09.DH -Inosilicates with 4-periodic single chains, Si4O12

09.DH.45 Aenigmatite (Na,Ca)4(Fe,Ti,Mg)12Si12O40 P1 1

09.DH.45 Dorrite Ca2Mg2Fe4(Al,Fe)4Si2O20 P1,P 1 Tri

09.DH.45 Krinovite NaMg2CrSi3O10 P1 1

09.DH.45 Rhonite Ca2(Mg,Fe,Fe,Ti)6(Si,Al)6O20 P1 1

09.DH.45 Sapphirine (Mg,Al)8(Al,Si)6O20 P1 1

09.DH.45 Serendibite Ca2(Mg,Al)6(Si,Al,B)6O20 P1 1

09.DH.45 Khmaralite! (Mg,Al,Fe)16(Al,Si,Be)12O40 P 2₁/c 2/m

09.DH.45 Makarochkinite! Ca2Fe4FeTiSi4BeAlO20 P1 1

09.DH.45 Welshite Ca4Mg9Sb3O4[Si6Be3AlFe2O36] P1 1

09.DH.45 Wilkinsonite Na2Fe4Fe2Si6O20 P1 1

Other Welshite Information

References:

NAME( Dana8) PHYS. PROP.(AmMin, V87:358 and v92:80) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Welshite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Ask about Welshite here :
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Print or Cut-and-Paste your Welshite Specimen Label here :

Welshite

Ca4Mg9Sb3O4[Si6Be3AlFe2O36]
Dana No: 69.02.01a.07 Strunz No: 09.DH.45
Locality:

Notes: