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Poldervaartite

Big Photo

Wessels Mine (Wessel's Mine), Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa
© Rob Lavinsky

Show Poldervaartite Photos (85)
Formula:
CaCa[SiO
 
3
OH](OH)
System:OrthorhombicColour:colourless, milky white, ...
Hardness:5
Name:For Arie Poldervaart (1918-1964), petrologist, Columbia University, New York


The Ca-dominant analogue of Olmiite.

Most (all?) "poldervaartites" seem to be olmiites, see http://www.mindat.org/mesg-7-104499.html.

Classification of Poldervaartite

IMA status:Approved 1992
Strunz 8th edition ID:8/B.22-25
Nickel-Strunz 10th (pending) edition ID:9.AF.90

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
Dana 8th edition ID:78.1.8.1

78 : Unclassified Silicates
1 : Miscellaneous
mindat.org URL:http://www.mindat.org/min-3252.html
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Type Occurrence of Poldervaartite

Type Locality:Wessels Mine (Wessel's Mine), Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa
Place of Conservation of Type Material:American Museum Natural History, New York T100728

Occurrences of Poldervaartite

Geological Setting:In massive manganese ore.

Physical Properties of Poldervaartite

Lustre:Vitreous, Sub-Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Comment:Vitreous on fractures
Colour:colourless, milky white, pink-white
Streak:white
Hardness (Mohs):5
Tenacity:Very brittle
Cleavage:None Observed
Density (measured):2.91(2) g/cm3
Density (calculated):2.9 g/cm3

Crystallography of Poldervaartite

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:Pbca {P21/b 21/c 21/a}
Cell Parameters:a = 9.398(1) Å, b = 9.139(2) Å, c = 10.535(2) Å
Ratio:a:b:c = 1.028 : 1 : 1.153
Unit Cell Volume:V 904.83 ų (Calculated from Unit Cell)
Z:8
Morphology:Prismatic, sheaves
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Poldervaartite

Type:Biaxial (+)
RI values: nα = 1.634 nβ = 1.640 nγ = 1.656
2V:Measured: 63° to 65°, Calculated: 64°
Maximum Birefringence:δ = 0.022

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r < v weak
Pleochroism:Weak
Comments:X= colorless
Y= light gray
Z= bluish gray

Chemical Properties of Poldervaartite

Formula:
CaCa[SiO
 
3
OH](OH)
Essential elements:Ca, H, Mn, O, Si
All elements listed in formula:Ca, H, O, Si
Common Impurities:Fe,Mg,H2O

Relationship of Poldervaartite to other Species

Series:Forms a series with Olmiite (see here)
Related Minerals - Nickel-Strunz Grouping):

- +
9.AF.05Sillimanite
Al
 
2
[O|SiO
 
4
]
9.AF.10Andalusite
Al
 
2
[O|SiO
 
4
]
9.AF.10Kanonaite
Mn
3+
 
Al[O|SiO
 
4
]
9.AF.15Kyanite
Al
 
2
[O|SiO
 
4
]
9.AF.20Mullite
Al
 
8
[(O,OH,F)|(Si,Al)O
 
4
]
 
4
9.AF.20Krieselite
(Al,Ga)
 
2
[(OH)
 
2
|GeO
 
4
]
9.AF.23Boromullite
Al
 
9
Si
 
2
BO
 
19
9.AF.25Yoderite
Mg(Al,Fe
3+
 
)
 
3
[O|OH|(SiO
 
4
)
 
2
]
9.AF.30Magnesiostaurolite
(Mg,Li,Fe
2+
 
)
 
1.5-2
Al
 
9
[O
 
6
|(OH)
 
2
|(SiO
 
4
)
 
4
]
9.AF.30Staurolite
(Fe
2+
 
,Mg,Zn)
 
1.5-2
Al
 
9
[O
 
6
|(OH,O)
 
2
|(SiO
 
4
)
 
4
]
9.AF.30Zincostaurolite
(Zn,Li,Fe
2+
 
,Mg)
 
<2
Al
 
9
[O
 
6
|(OH)
 
2
|(SiO
 
4
)
 
4
]
9.AF.35Topaz
Al
 
2
[(F,OH)
 
2
|SiO
 
4
]
9.AF.40Norbergite
Mg
 
3
[(F,OH)
 
2
|SiO
 
4
]
9.AF.45Alleghanyite
Mn
2+
5
[(OH)
 
2
|(SiO
 
4
)
 
2
]
9.AF.45Chondrodite
(Mg,Fe
2+
 
)
 
5
[(F,OH)
 
2
|(SiO
 
4
)
 
2
]
9.AF.45Reinhardbraunsite
Ca
 
5
[(OH,F)
 
2
|(SiO
 
4
)
 
2
]
9.AF.45Kumtyubeite
Ca
 
5
(SiO
 
4
)
 
2
F
 
2
9.AF.50Humite
(Mg,Fe
2+
 
)
 
7
[(F,OH)
 
2
|(SiO
 
4
)
 
3
]
9.AF.50Manganhumite
(Mn
2+
 
,Mg)
 
7
[(OH)
 
2
|(SiO
 
4
)
 
3
]
9.AF.50Unnamed (Ca-analogue of humite)
Ca
 
7
(SiO
 
4
)
 
3
(OH)
 
2
9.AF.55Clinohumite
(Mg,Fe
2+
 
)
 
9
[(F,OH)
 
2
|(SiO
 
4
)
 
4
]
9.AF.55Sonolite
Mn
2+
9
[(OH,F)
 
2
|(SiO
 
4
)
 
4
]
9.AF.55Hydroxylclinohumite
Mg
 
9
[(OH,F)
 
2
|(SiO
 
4
)
 
4
]
9.AF.60Leucophoenicite
Mn
2+
7
[(OH)
 
2
|(SiO
 
4
)
 
3
]
9.AF.65Ribbeite
(Mn
2+
 
,Mg)
 
5
[(OH)
 
2
|(SiO
 
4
)
 
2
]
9.AF.70Jerrygibbsite
Mn
2+
9
[(OH)
 
2
|(SiO
 
4
)
 
4
]
9.AF.75Franciscanite
Mn
2+
6
(V
5+
 
,[])
 
2
[(O,OH)
 
3
|SiO
 
4
]
 
2
9.AF.75Örebroite
Mn
2+
3
(Fe
3+
 
,Sb
5+
 
)[(O,OH)
 
3
|SiO
 
4
]
9.AF.75Welinite
Mn
2+
6
(W
6+
 
,Mg)
 
2
[(O,OH)
 
3
|SiO
 
4
]
 
2
9.AF.80Ellenbergerite
Mg
 
6
Al
 
6
Ti[(OH)
 
6
|(HSiO
 
4
)
 
4
|(SiO
 
4
)
 
4
]
9.AF.85Chloritoid
(Fe
2+
 
,Mg,Mn
2+
 
)Al
 
2
[O|(OH)
 
2
|SiO
 
4
]
9.AF.85Magnesiochloritoid
MgAl
 
2
[O|(OH)
 
2
|SiO
 
4
]
9.AF.85Ottrélite
(Mn
2+
 
,Fe
2+
 
,Mg)Al
 
2
[O|(OH)
 
2
|SiO
 
4
]
9.AF.90Olmiite
CaMn
2+
 
[SiO
 
3
(OH)](OH)

Other Names for Poldervaartite

Synonyms:
IMA1992-012
Other Languages:
German:Poldervaartit
Russian:Полдерваартит
Spanish:Poldervaartita

Other Information

Fluorescence in UV light:Deep red in SW
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 Poldervaartite

Reference List:Day, Y., Harlow G.E., and McGhie, A.R. (1993) American Mineralogist, 78, 1082-1087.

New Minerals (1997), New Minerals 1990-1994.

Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.

Internet Links for Poldervaartite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Poldervaartite in the Natural History Museum (London) online catalogue
  • Poldervaartite details from Handbook of Mineralogy (PDF)
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    Localities for Poldervaartite

    Hide Locality List
    The 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.
    (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.
    South Africa
     
    • Northern Cape Province
      • Kalahari manganese fields
        • Hotazel
    		Amer.Min.(1993) 78, 1082-1087; von Bezing, L. & Gutzmer, J. (1994): Das Kalahari Manganerzfeld und seine Mineralien (II). Mineralien-Welt, 5(5), 41-59. Gutzmer, J. & Cairncross, B. (2001): Seltene Mineralien aus dem Kalahari-Manganerzfeld, Südafrika. Lapis, 26(10), 32-42; Gutzmer, J. & Cairncross, B. (2002): Spectacular Minerals from the Kalahari Manganese Field, South Africa. Rocks & Minerals, 77(2), 94-107.
        • Kuruman
          • N'Chwaning Mines
    		No reference listed
    • Cairncross, B., Gutzmer, J. & Pretorius, A. (2002): Spektakulärer Neufund: Poldervaartit aus der N'Chwaning II - Mine, Kalahari, Südafrika. Lapis, 27(5), 30-34; Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, Menchetti, S. (2007): Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa), Mineralogical Magazine, 71, 193-291.. Pagano et al (2008) Mineralogical Record 39:373-381
    Mineral and/or Locality
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