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Johnwalkite

Big Photo

Champion Mine, Keystone, Keystone District, Pennington Co., South Dakota, USA
© 2008, JGW

Formula:
K(Mn
2+
 
,Fe
2+
 
,Fe
3+
 
)
 
2
(Nb
5+
 
,Ta
5+
 
)[O|PO
 
4
]
 
2
 · 2(H
 
2
O,OH)
System:OrthorhombicHardness:4
This page provides mineralogical data about Johnwalkite.

Classification of Johnwalkite

IMA status:Approved 1985
Strunz 8th edition ID:7/D.39-20
Nickel-Strunz 10th (pending) edition ID:8.DJ.05

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
J : With large and medium-sized cations, (OH, etc.):RO4 = 1:1
Dana 8th edition ID:42.7.11.2

42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
7 : (AB)2(XO4)Zq·xH2O
Hey's CIM Ref.:22.5.14

22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
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Type Occurrence of Johnwalkite

Type Locality:Champion Mine, Keystone, Keystone District, Pennington Co., South Dakota, USA
Year of Discovery:1986

Physical Properties of Johnwalkite

Hardness (Mohs):4

Crystallography of Johnwalkite

Crystal System:Orthorhombic
Cell Parameters:a = 7.51Å, b = 10.02Å, c = 6.5Å
Ratio:a:b:c = 0.75 : 1 : 0.649
Unit Cell Volume:V 489.13 ų (Calculated from Unit Cell)

Optical Data of Johnwalkite

Type:Biaxial (+)
RI values: nα = 1.748 nβ = 1.763 nγ = 1.840
2V:Measured: 53° , Calculated: 50°
Maximum Birefringence:δ = 0.092

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Dispersion:r > v strong

Chemical Properties of Johnwalkite

Formula:
K(Mn
2+
 
,Fe
2+
 
,Fe
3+
 
)
 
2
(Nb
5+
 
,Ta
5+
 
)[O|PO
 
4
]
 
2
 · 2(H
 
2
O,OH)
Essential elements:H, K, Mn, Nb, O, P
All elements listed in formula:Fe, H, K, Mn, Nb, O, P, Ta

Relationship of Johnwalkite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
8.DJ.05Olmsteadite
KFe
2+
2
(Nb
5+
 
,Ta
5+
 
)[O|PO
 
4
]
 
2
 · 2H
 
2
O
8.DJ.10Gatumbaite
CaAl
 
2
[OH|PO
 
4
]
 
2
 · H
 
2
O
8.DJ.15Camgasite
CaMg[OH|AsO
 
4
] · 5H
 
2
O
8.DJ.20Phosphofibrite
[K
 
<0.5
(H
 
2
O)
 
3
][(Fe
3+
 
,Cu)
 
8
(PO
 
4
)
 
6
(OH)
 
7
(H
 
2
O)
 
4
]
8.DJ.20Meurigite-K
[K(H
 
2
O)
 
2.5
][Fe
3+
8
(PO
 
4
)
 
6
(OH)
 
7
(H
 
2
O)
 
4
]
8.DJ.20Meurigite-Na
[Na(H
 
2
O)
 
2.5
][Fe
3+
8
(PO
 
4
)
 
6
(OH)
 
7
(H
 
2
O)
 
4
]
8.DJ.25Jungite
Ca
 
2
Zn
 
4
Fe
3+
8
[OH|PO
 
4
]
 
9
 · 16H
 
2
O
8.DJ.30Wycheproofite
NaAlZr[OH|PO
 
4
]
 
2
 · H
 
2
O
8.DJ.35Ercitite
Na
 
2
(H
 
2
O)
 
4
[Mn
3+
2
(OH)
 
2
(PO
 
4
)
 
2
]
8.DJ.40Mrázekite
Bi
 
2
Cu
 
3
[O|OH|PO
 
4
]
 
2
 · H
 
2
O
8.DJ.45Attikaite
Ca
 
3
Cu
 
2
Al
 
2
[AsO
 
4
]
 
4
(OH)
 
4
 · 2H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
22.5.1Vauquelinite
Pb
 
2
Cu[OH|PO
 
4
|CrO
 
4
]
22.5.2Embreyite
Pb
 
5
[PO
 
4
|CrO
 
4
]
 
2
 · H
 
2
O
22.5.3Cassedanneite
Pb
 
5
[VO
 
4
|CrO
 
4
]
 
2
 · H
 
2
O
22.5.4Fornacite
Pb
 
2
Cu[OH|AsO
 
4
|CrO
 
4
]
22.5.5Molybdofornacite
Pb
 
2
Cu[OH|(AsO
 
4
,PO
 
4
)|(MoO
 
4
,CrO
 
4
)]
22.5.6Mendozavilite
Na(Ca,Mg)
 
2
[Fe
 
6
(PO
 
4
)
 
2
(PMo
 
11
O
 
39
)(OH,Cl)
 
10
]·33H
 
2
O
22.5.7Paramendozavilite
NaAl
 
4
[Fe
 
7
(PO
 
4
)
 
5
(PMo
 
12
O
 
40
)(OH)
 
16
]·56H
 
2
O
22.5.8Betpakdalite
{Mg(H
 
2
O)
 
6
}Ca
 
2
(H
 
2
O)
 
13
[Mo
6+
8
As
5+
2
Fe
3+
3
O
 
36
(OH)](H
 
2
O)
 
4
22.5.9Natrobetpakdalite
(Na
 
2
,Ca)Fe
 
2
(As
 
2
Mo
 
6
O
 
28
)·15H
 
2
O
22.5.10Obradovicite
H
 
4
(K,Na)CuFe
 
2
AsO
 
4
(MoO
 
4
)
 
5
·12H
 
2
O
22.5.11Melkovite
CaFeH
 
6
(MoO
 
4
)
 
4
PO
 
4
·6H
 
2
O or near·
22.5.12Rankachite
(V
4+
 
,V
5+
 
)(W
6+
 
,Fe
3+
 
)
 
2
O
 
8
(OH)•(Ca
 
x
H
 
2
O
 
y
) with x ~ 0.5, y ~ 2.
22.5.13Olmsteadite
KFe
2+
2
(Nb
5+
 
,Ta
5+
 
)[O|PO
 
4
]
 
2
 · 2H
 
2
O

Other Names for Johnwalkite

Synonyms:
IMA1985-008
Other Languages:
German:Johnwalkit
Russian:Джонуолкит
Spanish:Johnwalkita

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 Johnwalkite

Reference List:American Mineralogist (1987): 72: 223.

Neues Jahrbuch für Mineralogie, Monatshefte (1986): 3: 115-120.

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    Localities for Johnwalkite

    (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.
    USA
     
    • South Dakota
      • Pennington Co.
        • Keystone District
          • Keystone
    		NJMM (1986), 115; HB4 (2000)
    Mineral and/or Locality
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    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 27th Oct 2009 02:05:52