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Medaite

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Molinello Mine, Graveglia Valley, Ne, Genova Province, Liguria, Italy
© Stephan Wolfsried

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Formula:
(Mn,Ca)
 
6
(V,As)Si
 
5
O
 
18
OH
System:MonoclinicColour:Brownish-red
Name:For Dr. Francesco Meda, an amateur mineralogist from Turin.
This page provides mineralogical data about Medaite.

Classification of Medaite

IMA status:Approved
Strunz 8th edition ID:8/C.34-14
Nickel-Strunz 10th (pending) edition ID:9.BJ.30

9 : SILICATES (Germanates)
B : Sorosilicates
J : Sorosilicates with Si3O10, Si4O11, etc. anions; cations in octahedral [6] and greater coordination
Dana 8th edition ID: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
Hey's CIM Ref.:17.7.5

17 : Silicates Containing other Anions
7 : Silicates with vanadate, arsenate or antimonate
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Type Occurrence of Medaite

Type Locality:Molinello Mine, Graveglia Valley, Ne, Genova Province, Liguria, Italy
Place of Conservation of Type Material:Institute of Mineralogy, Milan, Mineral Museums of Universities of Rome and Oslo, Norway.
Year of Discovery:1982
Geological Setting of type material:Manganese mine.

Physical Properties of Medaite

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

Crystallography of Medaite

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

Optical Data of Medaite

Type:Biaxial (+)
RI values: nα = 1.770 nβ = 1.780 nγ = 1.800
2V:Measured: 71° , Calculated: 72°
Maximum Birefringence:δ = 0.030

Chart 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 Medaite

Formula:
(Mn,Ca)
 
6
(V,As)Si
 
5
O
 
18
OH
Essential elements:H, Mn, O, Si, V
All elements listed in formula:As, Ca, H, Mn, O, Si, V
Common Impurities:Fe,H2O

Relationship of Medaite to other Species

Related Minerals - Nickel-Strunz Grouping):
9.BJ.05Orientite
Ca
 
2
MnMn
 
2
Si
 
3
O
 
10
(OH)
 
4
9.BJ.10Rosenhahnite
HCa
 
3
[Si
 
3
O
 
9
(OH)]
9.BJ.15Trabzonite
Ca
 
4
Si
 
3
O
 
10
·2H
 
2
O
9.BJ.20Thalénite-(Y)
Y
 
3
Si
 
3
O
 
10
(OH)
9.BJ.20Fluorthalénite-(Y)
Y
 
3
Si
 
3
O
 
10
F
9.BJ.25Tiragalloite
Mn
 
4
AsSi
 
3
O
 
12
(OH)
9.BJ.35Ruizite
Ca
 
2
Mn
3+
2
[(OH)
 
2
|H
 
2
Si
 
4
O
 
13
] · 2H
 
2
O
9.BJ.40Ardennite-(As)
Mn
2+
4
[(Al,Mg)
 
6
][(OH)
 
6
|(AsO
 
4
,VO
 
4
)|(SiO
 
4
)
 
2
|Si
 
3
O
 
10
]
9.BJ.40Ardennite-(V)
Mn
2+
4
[Al
 
4
(Mg,Al,Fe
3+
 
,Mn
3+
 
)
 
2
][(OH)
 
6
|(VO
 
4
,SiO
 
4
)|(SiO
 
4
)
 
2
|Si
 
3
O
 
10
]
9.BJ.45Kilchoanite
Ca
 
3
Si
 
2
O
 
7
9.BJ.50Kornerupine
Mg
 
3
Al
 
6
(Si,Al,B)
 
5
O
 
21
(OH)
9.BJ.50Prismatine
([ ],Fe,Mg)(Mg,Al,Fe)
 
5
Al
 
4
Si
 
2
(Si,Al)
 
2
(B,Si,Al)(O,OH,F)
 
22
9.BJ.55Zunyite
Al
 
13
Si
 
5
O
 
20
(OH,F)
 
18
Cl
9.BJ.60Hubeite
Ca
 
2
Mn
2+
 
Fe
3+
 
[HSi
 
4
O
 
13
] · 2H
 
2
O
9.BJ.65Cassagnaite
(Ca,Mn
2+
 
)
 
4
(Fe
3+
 
,Mn
3+
 
,Al)
 
4
(V
3+
 
,Mg,Al)
 
2
[(O,OH)
 
4
|(OH)
 
4
|(SiO
 
4
)
 
2
|Si
 
3
O
 
10
]
Related Minerals - Hey's Index Grouping:
17.7.1Suzukiite
BaVSi
 
2
O
 
7
17.7.2Franciscanite
Mn
3+
6
V
5+
0.5
[(O,OH)
 
3
|SiO
 
4
]
17.7.3Kurumsakite
(Zn,Ni,Cu)
 
8
Al
 
8
V
 
2
Si
 
5
O
 
35
·27H
 
2
O (or near)
17.7.4Ardennite-(As)
Mn
2+
4
[(Al,Mg)
 
6
][(OH)
 
6
|(AsO
 
4
,VO
 
4
)|(SiO
 
4
)
 
2
|Si
 
3
O
 
10
]
17.7.6Johninnesite
Na
 
2
Mg
 
5
Mn
 
12
As
 
2
Si
 
12
O
 
43
(OH)
 
6
17.7.7Tiragalloite
Mn
 
4
AsSi
 
3
O
 
12
(OH)
17.7.8Dixenite
CuMn
2+
14
Fe
2+
 
[(OH)
 
6
|(AsO
 
3
)
 
5
|AsO
 
4
|(SiO
 
4
)
 
2
]
17.7.9Asbecasite
Ca
 
3
(Ti,Sn
4+
 
)Be
 
2
[(AsO
 
3
)
 
3
|SiO
 
4
]
 
2
17.7.10Mcgovernite
(Mn,Mg,Zn)
 
273
As
3+
~12
As
5+
~30
Si
 
~42
O
 
324
(OH)
 
252
17.7.11Kraisslite
(Mn
2+
 
,Mg)
 
24
Zn
 
4
[(OH)
 
12
|(AsO
 
4
)
 
4
|(SiO
 
4
)
 
8
]
17.7.12Schallerite
(Mn,Fe)
 
16
Si
 
12
As
 
3
O
 
36
(OH)
 
17
17.7.13Nelenite
(Mn,Fe)
 
16
Si
 
12
As
 
3
O
 
36
(OH)
 
17
17.7.14Kolicite
Mn
2+
7
Zn
 
4
[(OH)
 
8
|(AsO
 
4
)
 
2
|(SiO
 
4
)
 
2
]
17.7.15Yeatmanite
Mn
2+
7
Zn
 
8
Sb
5+
2
[O
 
3
|SiO
 
4
]
 
4
17.7.16Welshite
Ca
 
4
Mg
 
9
Sb
 
3
O
 
4
[Si
 
6
Be
 
3
AlFe
 
2
O
 
36
]
17.7.17Katoptrite
(Mn
2+
 
,Mg)
 
13
(Al,Fe
3+
 
)
 
4
Sb
5+
2
[O
 
10
|SiO
 
4
]
 
2
17.7.18Parwelite
(Mn,Mg,Ca)
 
5
Sb(As,Si)
 
2
O
 
12
17.7.19Långbanite
(Mn
2+
 
,Ca)
 
4
(Mn
3+
 
,Fe
3+
 
)
 
9
Sb
5+
 
[O
 
8
|SiO
 
4
]
 
2
17.7.20Chapmanite
Fe
3+
2
Sb
3+
 
[OH|(SiO
 
4
)
 
2
]
17.7.21Cervandonite-(Ce)
(Ce,Nd,La)(Fe,Ti,Al)
 
3
SiAs(Si,As)O
 
13

Other Names for Medaite

Synonyms:
IMA1979-062
German names:
Medait
Russian names:
Медаит
Spanish names:
Medaita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Medaite

Reference List:American Mineralogist (1982): 67: 85-89.

Acta Crystallographica: 37: 1972-1978.

Internet Links for Medaite

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    Localities for Medaite

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Italy
     
    • Liguria
      • 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
    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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