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Orange, brownish orange
Crystal System:
Named after Paolo Onofrio Tiragallo (1905, Carro, La Spezia, Liguria, Italy - 1987), distinguished amateur mineralogist. Conservator and curator of the mineralogical collection of the University of Genoa.
Tiragalloite belongs to a rare class of compounds with As atoms replacing Si atoms in silicate anions, the so-called arsenosilicates (analoguous to the more common alumosilicates and borosilicates, in which Si atoms are replaced by Al atoms and B atoms, respectively). It contains isolated chains consisting of one (ASO4) tetrahedron and three (SiO4) tetrahedra, which are linked by sharing corners. One oxygen atom is protonated, resulting in the anion formula (HAsSi3O13)8-. The tetrahedral sites in the anion are ordered in that the As atoms are only found at the end of the chains, and there is exactly one As atom in each anion.

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Classification of TiragalloiteHide

Approval Year:

9 : SILICATES (Germanates)
B : Sorosilicates
J : Sorosilicates with Si3O10, Si4O11, etc. anions; cations in octahedral [6] and greater coordination

57 : SOROSILICATES Si3O10 Groups and Larger Noncyclic Groups
2 : Insular Si3O10 and Larger Noncyclic Groups with [Si4O13] groups

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

Physical Properties of TiragalloiteHide

Transparent, Translucent
Orange, brownish orange
Good on {100}.
Distinct parting, normal to elongation.

Optical Data of TiragalloiteHide

Biaxial (+)
RI values:
nα = 1.745 nβ = 1.751 nγ = 1.760
Measured: 38° to 46°, Calculated: 80°
Max Birefringence:
δ = 0.015
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:

Chemical Properties of TiragalloiteHide

Common Impurities:

Crystallography of TiragalloiteHide

Crystal System:
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 6.66(1) Å, b = 19.92(2) Å, c = 7.67(1) Å
β = 95.71(1)°
a:b:c = 0.334 : 1 : 0.385
Unit Cell V:
1,012.51 ų (Calculated from Unit Cell)
Space group P21/n.

Epitaxial Relationships of TiragalloiteHide

Epitaxial Minerals:
Epitaxy Comments:
(010)[001]tir // (010)[100]rho (Roth & Meisser, 2011)

Type Occurrence of TiragalloiteHide

Synonyms of TiragalloiteHide

Other Language Names for TiragalloiteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Rhodonite5 photos of Tiragalloite associated with Rhodonite on

Related Minerals - Nickel-Strunz GroupingHide

9.BJ.05OrientiteCa8Mn3+10(SiO4)3(Si3O10)3(OH)10 · 4H2O Orth.
9.BJ.15TrabzoniteCa4(Si3O9)(OH)2Orth. mm2 : Ama2
9.BJ.35RuiziteCa2Mn3+2[Si4O11(OH)2](OH)2·2H2OMon. 2
9.BJ.40Ardennite-(As)Mn2+4Al4(AlMg)(AsO4)(SiO4)2(Si3O10)(OH)6Orth. mmm (2/m 2/m 2/m)
9.BJ.40Ardennite-(V)Mn2+4Al4(AlMg)(VO4)(SiO4)2(Si3O10)(OH)6Orth. mmm (2/m 2/m 2/m) : Pmmn
9.BJ.50KornerupineMg3Al6(Si,Al,B)5O21(OH)Orth. mmm (2/m 2/m 2/m)
9.BJ.55ZunyiteAl13Si5O20(OH,F)18ClIso. 4 3m : F4 3m
9.BJ.60HubeiteCa2Mn2+Fe3+[HSi4O13] · 2H2OTric.
9.BJ.65Cassagnaite(Ca,Mn2+)4(Fe3+,Mn3+,Al)4(V3+,Mg,Al)2(Si3O10)(SiO4)2(OH,O)8Orth. mmm (2/m 2/m 2/m) : Cmcm

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

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)
17.7.9AsbecasiteCa3(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
17.7.14KoliciteMn2+7Zn4(AsO4)2(SiO4)2(OH)8Orth. mmm (2/m 2/m 2/m) : Cmca
17.7.16WelshiteCa4Mg9Sb3O4[Si6Be3AlFe2O36]Tric. 1 : P1
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

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 TiragalloiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Rendiconti Società Italiana di Mineralogia e Petrologia (1979) 35: 145-149.
Gramaccioli, C.M., Griffin, W.L., Mottana, A. (1980) Tiragalloite, Mn4[AsSi3O12(OH)], a new mineral and the first example of arsenatotrisilicate. American Mineralogist: 65: 947-952.
Gramaccioli, C.M., Pilati, T., Liborio, G. (1979) Structure of manganese(II) arsenatotrisilicate, Mn4[AsSi3O12(OH)]: the presence of a new tetrapolyphosphate-like anion. Acta Crystallographica: B35: 2287-2291.
Nagashima, M., Armbruster, T. (2010) Ardennite, tiragalloite and medaite: structural control of (As5+,V5+,Si4+)O4 tetrahedra in silicates. Mineralogical Magazine: 74: 55-71.

Internet Links for TiragalloiteHide

Localities for TiragalloiteHide

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.
  • Tyrol
    • East Tyrol
      • Kals valley
Abrecht, J. (1990) An As-rich manganiferous mineral assemblage from the Ködnitz Valley (Eastern Alps, Austria): Geology, mineralogy, genetic considerations, and implications for metamorphic Mn deposits. Neues Jahrbuch für Mineralogie, Monatshefte 1990, 363-375.
    • North Tyrol
      • Sill valley (Wipp valley)
        • Navis valley
          • Navis
BRANDSTÄTTER, F., GRILL, J., NIEDERMAYR, G. & WALTER, F. (2015): 1927) Bementit, Bixbyit, Kutnohorit, Manganberzeliit, Tilasit, Tiragalloit, Todorokit und andere Mineralien von Navis, Tirol. Pp. 232-234 in NIEDERMAYR, G. et al. (2015): Neue Mineralfunde aus Österreich LIX. Carinthia II, 205./125., 207-280.
  • Aosta Valley
    • Saint-Marcel
Cenki-Tok, B. & Chopin, C. (2006): Coexisting calderite and spessartine garnets in eclogite-facies metacherts of the Western Alps. Mineralogy and Petrology, 88, 47-68.
  • Liguria
    • Genova Province
      • Ne
        • Graveglia Valley
Redazionale (2005): Sistematica ligure: resoconto 2005. Notiziario di Mineralogia del Ferrania Club, 19 , 3-5.
[Rend.Soc.It.Min.Petrol.(1979) 35, 145-149; MinRec 32:355]
          • Reppia
Rivista Mineralogica Italiana, (4), 131
  • Lombardy
    • Sondrio Province
      • Valtellina
Lapis, 19 (10), 15-21+86.
          • Lanterna Valley
            • Lanzada
Callegari, A., Sciesa, E., Bedognè, F. (1992) Primo ritrovamento di tiragalloite in Valmalenco (Sondrio, Italia Settentrionale). Il Naturalista Valtellinese - Atti Mus. civ. Stor. nat. Morbegno, 3, 3-9. Bedognè, F., Montrasio, A., Sciesa, E. (1993) I minerali della provincia di Sondrio: Valmalenco. Bettini, Sondrio, 275 pp. Bedognè, F., Montrasio, A., Sciesa, E. (2006) I minerali della media-alta Valtellina, delle Orobie valtellinesi e della Val Poschiavo. Aggiornamenti sulle altre località della provincia di Sondrio. Bettini, Sondrio, 255 pp. Bedognè, F. (2011) Microminerali della Valmalenco. Nuove segnalazioni e aggiornamenti. Riv. Mineral. It., 35, 1, 40-45.
  • Piedmont
    • Cuneo Province
      • Maira Valley
        • Canosio
          • Vallone della Valletta
Bracco R. (2014) Sempre novità "estere". Segnalazioni in breve. Prie, 10, 48; Cámara, F., Bittarello, E., Ciriotti, M.E., Nestola, F., Radica, F., Marchesini, M. (2015) Arsenic-bearing new mineral species from Valletta mine, Maira Valley, Piedmont, Italy: II. Braccoite, NaMn2+5[Si5AsO17(OH)](OH), description and crystal structure. Mineralogical Magazine, 79, 171-189; Kampf, A.R., Cámara, F., Ciriotti, M.E., Nash, B.P., Balestra, C., Chiappino, L. (2016): Castellaroite, Mn2+3(AsO4)2⋅4.5H2O, a new mineral from Italy related to metaswitzerite. European Journal of Mineralogy, 28, 687-696; Cámara, F., Bittarello, E., Ciriotti, M.E., Nestola, F., Radica, F., Massimi, F., Balestra, C., Bracco, R. (2017a) As-bearing new mineral species from Valletta mine, Maira Valley, Piedmont, Italy: III. Canosioite, Ba2Fe3+(AsO4)2(OH), description and crystal structure. Mineralogical Magazine, 81, 305–317.
    • Torino Province
      • Susa Valley
        • Salbertrand
Piccoli, G.C., Maletto, G., Bosio, P., Lombardo, B. (2007): Minerali del Piemonte e della Valle d'Aosta. Associazione Amici del Museo "F. Eusebio" Alba, Ed., Alba (Cuneo) 607 pp.
Piccoli, G.C., Maletto, G., Bosio, P., Lombardo, B. (2007). Minerali del Piemonte e della Valle d'Aosta. Associazione Amici del Museo "F. Eusebio" Alba, Ed., Alba (Cuneo) 607 pp.
  • Kyushu Region
    • Nansei Archipelago
      • Kagoshima Prefecture
        • Amami-Oshima Island
          • Yamato-son (Yamato village)
Fujiwara et al. (2005) Kobutsu-Gakkai Koen-Yoshi, 149; Nakao et al. (2005): Annual Meeting of the Mineral. Soc. of Japan, 129.
  • Grischun (Grisons; Graubünden)
    • Hinterrhein Valley
      • Ferrera Valley
        • Ausserferrera
J. Brugger et al.: Am. Min. 91:937-943(2006)
      • Rheinwald
        • Splügen
Stalder, H. A., Wagner, A., Graeser, S. and Stuker, P. (1998): "Mineralienlexikon der Schweiz", Wepf (Basel), p. 404.; Roth, P. & Meisser, N. (2011): I minerali dell'Alpe Tanatz. Passo dello Spluga (Grigioni, Svizzera). Rivista Mineralogica Italiana, 2/2011, 90-99; Roth, P. (2011): Epitassia di tiragalloite su rodonite, Alpe Tanatz, Passo dello Spluga (Grigioni, Svizzera). Rivista Mineralogica Italiana, 2/2011, 100-103.
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