Tiragalloite Mineral Data

Tiragalloite Mineral Data +

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General Tiragalloite Information

Chemical Formula:

Mn++4As+++++Si3O12(OH)

Composition:

Molecular Weight = 587.93 gm

Manganese 37.38 % Mn 48.26 % MnO

Silicon 14.33 % Si 30.66 % SiO₂

Arsenic 12.74 % As 19.55 % As₂O₅

Hydrogen 0.17 % H 1.53 % H₂O

Oxygen 35.38 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₄AsSi₃O₁₂(OH)

Environment:

Veinlets cutting massive braunite and quartz.

IMA Status:

Approved IMA 1980

Locality:

Molinello, Chiavari, Val Graveglia, Liguria, Italy. Link to MinDat.org Location Data.

Name Origin:

Named for Paolo Tiragallo (1905-).

Synonym:

ICSD 8188

PDF 33-889

Tiragalloite Image

Images:

Tiragalloite

Comments: Orange crystals of tiragalloite in matrix.
Location: Molinello Mine, Val Graveglia, Liguria, Italy. Scale: Picture size 7 mm.
© Thomas Witzke / Abraxas-Verlag

Tiragalloite Crystallography

Axial Ratios:

a:b:c =0.3343:1:0.382

Cell Dimensions:

a = 6.66, b = 19.92, c = 7.61, Z = 4; beta = 95.7° V = 1,004.61 Den(Calc)= 3.89

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/n

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

By Intensity(I/I_o): 3.006(1), 3.267(0.71), 3.042(0.66),

Crystal Structure:

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Gramaccioli C M , Pilati T , Liborio G , Acta Crystallographica, Section B , 35 (1979) p.2287-2291, Structure of a manganese(II) arsenatotrisilicate, Mn4[AsSi3O12(OH)]:, The presence of a new tetrapolyphosphate-like anion, Locality: Molinello, near Chiavari, Liguria,, Note: Displacement parameters taken from ICSD

Physical Properties of Tiragalloite

Cleavage:

[100] Good, [hk0] Parting

Color:

Orange.

Density:

3.84

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

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

Luster:

Subadamantine

Streak:

white

Optical Properties of Tiragalloite

Gladstone-Dale:

CI meas= -0.001 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.012 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1933,KPDmeas= 0.1958,KC= 0.1957

Optical Data:

Biaxial (+), a=1.745, b=1.751, g=1.76, bire=0.0150, 2V(Calc)=80, 2V(Meas)=38-46.

Calculated Properties of Tiragalloite

Electron Density:

r_electron=3.66 gm/cc
note: r_Tiragalloite=3.84 gm/cc.

Fermion Index

Fermion Index = 0.00686
Boson Index = 0.99314

Photoelectric:

PE_Tiragalloite= 18.92 barns/electron
U=PE_Tiragalloite x r_electron= 69.20 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Tiragalloite is Not Radioactive

Tiragalloite Classification

Dana Class:

57.2.1.1 (57)Sorosilicate Insular Si3O10 and Larger Noncyclic Groups

(57.2)with [Si4O13] groups

(57.2.1)Dana Group

57.2.1.1 Tiragalloite Mn4AsSi3O12(OH) P 2₁/n 2/m

Strunz Class:

VIII/F.24-12 VIII - Silicates

VIII/F - Inosilicates (chain and band) Quadruplet chains [Si4O12]8-

VIII/F.24 - Balangeroite - Raite series

VIII/F.24-10 Balangeroite (Mg,Fe,Fe,Mn)42Si16O54(OH)40 P 2/n 2/m

VIII/F.24-12 Tiragalloite Mn4AsSi3O12(OH) P 2₁/n 2/m

VIII/F.24-20* Gageite (Mn,Mg,Zn)42Si16O54(OH)40 P1 1

VIII/F.24-20 Gageite-2M (Mn,Mg,Zn)42Si16O54(OH)40 P 2/n 2/m

VIII/F.24-30 Raite Na3Mn3Ti0.25Si8O20(OH)2·10(H2O) C 2/m 2/m

Other Tiragalloite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Print or Cut-and-Paste your Tiragalloite Specimen Label here :

Tiragalloite

Mn++4As+++++Si3O12(OH)
Dana No: 57.2.1.1 Strunz No: VIII/F.24-12
Locality:

Notes: