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Medaite

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About MedaiteHide

Formula:
Mn2+6V5+Si5O18(OH)
Mn may be replaced by minor Ca, and V by minor As.
Colour:
Brownish-red
Lustre:
Sub-Adamantine
Specific Gravity:
3.65 - 3.75
Crystal System:
Monoclinic
Name:
Named in 1981 by Carlo M. Gramaccioli, William L. Giffin, and Annibale Mottana in honor of Dr. Francesco Meda (1926 - 1977), an amateur mineralogist from Turin whose 'enthusiastic activity as a teacher has contributed to making mineralogy popular in Italy'.
Isostructural with:
The V analogue of arsenmedaite.


Classification of MedaiteHide

Approved
9.BJ.30

9 : SILICATES (Germanates)
B : Sorosilicates
J : Sorosilicates with Si3O10, Si4O11, etc. anions; cations in octahedral [6] and greater coordination
57.4.1.1

57 : SOROSILICATES Si3O10 Groups and Larger Noncyclic Groups
4 : Insular Si3O10 and Larger Noncyclic Groups with groups with 6 or more tetrahedra
17.7.5

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

Physical Properties of MedaiteHide

Sub-Adamantine
Transparency:
Translucent
Colour:
Brownish-red
Cleavage:
Distinct/Good
{100}
Parting:
Distinct normal to elongation
Density:
3.65 - 3.75 g/cm3 (Measured)    3.7 g/cm3 (Calculated)

Optical Data of MedaiteHide

Type:
Biaxial (+)
RI values:
nα = 1.770 nβ = 1.780 nγ = 1.800
2V:
Measured: 71° , Calculated: 72°
Max Birefringence:
δ = 0.030
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
r > v distinct
Pleochroism:
Weak
Comments:
Dark to lighter orange

Chemical Properties of MedaiteHide

Formula:
Mn2+6V5+Si5O18(OH)

Mn may be replaced by minor Ca, and V by minor As.
Common Impurities:
Fe,H2O

Crystallography of MedaiteHide

Crystal System:
Monoclinic
Cell Parameters:
a = 6.71 Å, b = 28.94 Å, c = 7.57 Å
β = 95.4°
Ratio:
a:b:c = 0.232 : 1 : 0.262
Unit Cell V:
1,463.47 ų (Calculated from Unit Cell)

Type Occurrence of MedaiteHide

Place of Conservation of Type Material:
Institute of Mineralogy, Milan, Mineral Museums of Universities of Rome and Oslo, Norway.
Geological Setting of Type Material:
Manganese mine.

Synonyms of MedaiteHide

Other Language Names for MedaiteHide

German:Medait
Russian:Медаит
Spanish:Medaita

Common AssociatesHide

Associated Minerals Based on Photo Data:
Pyroxmangite2 photos of Medaite associated with Pyroxmangite on mindat.org.
Ganophyllite1 photo of Medaite associated with Ganophyllite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.BJ.05OrientiteCa8Mn3+10(SiO4)3(Si3O10)3(OH)10 · 4H2O Orth.
9.BJ.10RosenhahniteHCa3[Si3O9(OH)]Tric.
9.BJ.15TrabzoniteCa4(Si3O9)(OH)2Orth. mm2 : Ama2
9.BJ.20Thalénite-(Y)Y3Si3O10FMon.
9.BJ.25TiragalloiteMn2+4As5+Si3O12(OH)Mon. 2/m
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.45KilchoaniteCa6(SiO4)(Si3O10)Orth.
9.BJ.50KornerupineMg3Al6(Si,Al,B)5O21(OH)Orth. mmm (2/m 2/m 2/m)
9.BJ.50Prismatine(◻,Fe,Mg)(Mg,Al,Fe)5Al4Si2(Si,Al)2(B,Si,Al)(O,OH,F)22Orth.
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

17.7.1SuzukiiteBaVSi2O7Orth.
17.7.2FranciscaniteMn2+6(V5+,☐)2(SiO4)2(O,OH)6Hex.
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)
17.7.6JohninnesiteNa2Mn2+9Mg7(OH)8[AsO4]2[Si6O17]2Tric.
17.7.7TiragalloiteMn2+4As5+Si3O12(OH)Mon. 2/m
17.7.8DixeniteCuMn2+14Fe2+(SiO4)2(As5+O4)(As3+O3)5(OH)6Trig.
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
17.7.13Nelenite(Mn,Fe)16(Si12O30)(OH)14[As3+3O6(OH)3]Mon.
17.7.14KoliciteMn2+7Zn4(AsO4)2(SiO4)2(OH)8Orth. mmm (2/m 2/m 2/m) : Cmca
17.7.15YeatmaniteZn6Mn2+9Sb5+2(SiO4)4O12Tric.
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 MedaiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Gramaccioli, C.M., Liborio, G., Pilati, T. (1981) Structure of medaite, Mn6[VSi5O18(OH)]: the presence of a new kind of heteropolysilicate anion. Acta Crystallographica: B37: 1972-1978.
Gramaccioli, C.M., Griffin, W.L., Mottana, A. (1982) Medaite, Mn6[VSi5O18(OH)], a new mineral and the first example of vanadatopentasilicate ion. American Mineralogist: 67: 85-89.
Nagashima, M. and 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 MedaiteHide

Localities for MedaiteHide

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.
Italy
 
  • Liguria
    • Genova and La Spezia Provinces
      • Tre Monti mining concession
        • Castiglione Chiavarese and Maissana
Castellaro, F., Passarino, G. (2011): I minerali di Monte Alpe. Sezione dell'antica Concessione Tre Monti (La Spezia e Genova). Rivista Mineralogica Italiana. 4/2011, 214-224.
    • Genova Province
      • Ne
        • Graveglia Valley
Redazionale (2005): Sistematica ligure: resoconto 2005. Notiziario di Mineralogia del Ferrania Club, 19 , 3-5.
[Amer.Min.(1982) 67, 85-89; MinRec 32:355]
          • Reppia
Rivista Mineralogica Italiana, (4), 131
Japan
 
  • Kyushu Region
    • Nansei Archipelago
      • Kagoshima Prefecture
        • Amami-Oshima Island
          • Yamato-son (Yamato village)
Go Ito pers. comm.
Switzerland
 
  • Grischun (Grisons; Graubünden)
    • Hinterrhein Valley
      • Ferrera Valley
        • Ausserferrera
J. Brugger et al.: Can. Mineral. 41:1423-1431 (2003); American Mineralogist: 91: 937-943.
Mineral and/or Locality  
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