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Trigonite

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About TrigoniteHide

Formula:
Pb3Mn2+(AsO3)2(HAsO3)
Colour:
Yellow to yellow-brown, dark brown or black; pale yellow to brownish yellow in transmitted light
Lustre:
Adamantine, Vitreous
Hardness:
2 - 3
Specific Gravity:
6.1 - 7.1
Crystal System:
Monoclinic
Name:
From the Greek τρίγωνον, "trigonon", a triangle, alluding to its common crystal shape.
This page provides mineralogical data about Trigonite.


Classification of TrigoniteHide

Approved, 'Grandfathered' (first described prior to 1959)
4.JB.40

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
B : Arsenites, antimonites, bismuthites; with additional anions, without H2O
45.1.2.1

45 : ACID AND NORMAL ANTIMONITES AND ARSENITES
1 : Miscellaneous

Physical Properties of TrigoniteHide

Adamantine, Vitreous
Transparency:
Translucent
Colour:
Yellow to yellow-brown, dark brown or black; pale yellow to brownish yellow in transmitted light
Streak:
Yellow
Hardness:
2 - 3 on Mohs scale
Cleavage:
Perfect
On {010}, perfect; on {101}, good.
Fracture:
Irregular/Uneven
Density:
6.1 - 7.1 g/cm3 (Measured)    6.35 g/cm3 (Calculated)

Optical Data of TrigoniteHide

Type:
Biaxial (-)
RI values:
nα = 2.070 nβ = 2.100 nγ = 2.120
Max Birefringence:
δ = 0.050
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
r < v strong
Comments:
2V = very large

Chemical Properties of TrigoniteHide

Formula:
Pb3Mn2+(AsO3)2(HAsO3)
IMA Formula:
Pb3Mn2+(AsO3)2(AsO2OH)

Crystallography of TrigoniteHide

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Cell Parameters:
a = 7.258 Å, b = 6.822 Å, c = 11.088 Å
β = 91.45°
Ratio:
a:b:c = 1.064 : 1 : 1.625
Unit Cell V:
548.84 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals domatic with a trigonal outline from the development of numerous domatic forms including c _s, and _p; also complexly modified; thick tabular, flattened on {010}; subparallel growths.
Comment:
Space Group: Pn

Type Occurrence of TrigoniteHide

Place of Conservation of Type Material:
Swedish Museum of Natural History, Stockholm, Sweden.
Geological Setting of Type Material:
Metamorphosed Fe-Mn ore body.
Associated Minerals at Type Locality:

Other Language Names for TrigoniteHide

German:Trigonit
Spanish:Trigonita

Related Minerals - Nickel-Strunz GroupingHide

4.JB.05Fetiasite(Fe3+,Fe2+,Ti)3(As2O5)O2Mon.
4.JB.10ManganarsiteMn3(As2O4)(OH)4
4.JB.15MagnussoniteMn10As6O18(OH,Cl)2Iso. m3m (4/m 3 2/m) : Ia3d
4.JB.15UM1984-09-AsO:ClHMnMn10As6O18(OH)ClTet. 4/mmm (4/m 2/m 2/m) : I41/acd
4.JB.20ArmangiteMn2+26(AsO3)14(HAsO3)4(CO3)Trig. 3 : P3
4.JB.25NanlingiteNa(Ca5Li)Mg12(AsO3)2[Fe(AsO3)6]F14Trig.
4.JB.30AsbecasiteCa3(Ti,Sn4+)Be2(AsO3)6(SiO4)2Trig. 3m : P3c1
4.JB.35StenhuggariteCaFeSb(AsO3)2OTet.
4.JB.45FinnemanitePb5(AsO3)3ClHex. 6/m : P63/m
4.JB.50GebharditePb8(As2O5)2OCl6Mon.
4.JB.55DerbyliteFe3+4Ti3Sb3+O13(OH)Mon. 2/m : P21/m
4.JB.55Tomichite(V,Fe)4Ti3AsO13(OH)Mon.
4.JB.55Graeserite(Fe3+ ,Ti)4Ti3AsO13(OH)Mon.
4.JB.60Hemloite(Ti,V3+,Fe3+,Al)12(As3+,Sb3+)2O23(OH)Tric. 1 : P1
4.JB.65FreediteCu+Pb8(AsO3)2O3Cl5Mon. 2/m : B2/m
4.JB.70GeorgiadèsitePb4(AsO3)Cl4(OH)Mon.
4.JB.75Ekatite(Fe3+,Fe2+,Zn)12(AsO3)6(AsO3,HSiO4)2(OH)6Hex.

Related Minerals - Dana Grouping (8th Ed.)Hide

45.1.2.2RouseitePb2Mn2+[AsO3]2 · 2H2OTric.

Other InformationHide

Notes:
Soluble in dilute acids.
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 TrigoniteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Flink (1920) Geologiska Föeningens I Stockholm Förhandlinger: 42: 436-439.
American Mineralogist (1921): 6: 93-94.
Larsen, E.S. and Berman, H. (1934) The Microscopic Determination of the Nonopaque Minerals, Second edition, USGS Bulletin 848: 209.
Pertlik, F. (1978) The crystal structure of trigonite, Pb3Mn(AsO3)2(AsO2OH). Tschermaks Mineralogische und Petrographische Mitteilungen: 25: 95-105.
Pertlik, F. (1987) [Crystal structure refinement of trigonite, Pb3Mn(AsO3)2 AsO2OH), with a remark on errors in inorganic crystal structure databases.] Österreichische Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Klasse, Anzeiger, 124, 81–84 (in German).
Mineralogical Abstracts (1989): 40: 1661.
Welin, E. (1968) X-ray powder data for minerals from Långban and the related mineral deposits of Central Sweden. Arkiv Mineral. Geol., 4(30), 499–541.

Internet Links for TrigoniteHide

Localities for TrigoniteHide

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.
Sweden (TL)
 
  • Värmland
    • Filipstad
Geologiska Föreningens I Stockholm. Förhandlinger, Stockholm (1920) 42, 436; Rocks & Min.: 62:166; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 1033; 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.
Mineral and/or Locality  
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