Poldervaartite
A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
About Poldervaartite
Arie Poldervaart
Formula:
CaCa[SiO3(OH)](OH)
Colour:
colourless, milky white, pink-white
Lustre:
Vitreous, Sub-Vitreous
Hardness:
5
Specific Gravity:
2.91
Crystal System:
Orthorhombic
Name:
Name in honor of Arie Poldervaart (6 July 1918, Bandung, Indonesia – 28 October 1964, Manhattan, New York, USA), petrologist at Columbia University, New York. He made important contributions to the understanding of the South African Karoo dolerites and Archean rocks in the Kakamas area of northwest Cape Province.
The Ca-dominant analogue of Olmiite.
Note: Most (all?) "poldervaartites" seem to be olmiites, see http://www.mindat.org/mesg-7-104499.html.
Visit gemdat.org for gemological information about Poldervaartite.
Note: Most (all?) "poldervaartites" seem to be olmiites, see http://www.mindat.org/mesg-7-104499.html.
Visit gemdat.org for gemological information about Poldervaartite.Unique Identifiers
Mindat ID:
3252
Long-form identifier:
mindat:1:1:3252:6
IMA Classification of Poldervaartite
Approved
IMA Formula:
Ca(Ca,Mn2+)(SiO3OH)(OH)
Approval year:
1992
First published:
1993
Classification of Poldervaartite
9.AF.90
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
78.1.8.1
78 : Unclassified Silicates
1 : Miscellaneous
78 : Unclassified Silicates
1 : Miscellaneous
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Pdv | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Poldervaartite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Poldervaartite
Vitreous, Sub-Vitreous
Transparency:
Transparent, Translucent
Comment:
Vitreous on fractures
Colour:
Colourless, milky white, pink-white
Streak:
White
Hardness:
5 on Mohs scale
Tenacity:
Very brittle
Cleavage:
None Observed
Density:
2.91(2) g/cm3 (Measured) 2.9 g/cm3 (Calculated)
Optical Data of Poldervaartite
Type:
Biaxial (+)
RI values:
nα = 1.634 nβ = 1.64 nγ = 1.656
2V:
Measured: 63° to 65°, Calculated: 64°
Max. Birefringence:
δ = 0.022
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r < v weak
Pleochroism:
Weak
Comments:
X= colorless
Y= light gray
Z= bluish gray
Y= light gray
Z= bluish gray
Chemistry of Poldervaartite
Mindat Formula:
CaCa[SiO3(OH)](OH)
Element Weights:
Elements listed:
Common Impurities:
Fe,Mg,H2O
Crystallography of Poldervaartite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbca
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 V:
904.83 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Prismatic, sheaves
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0010292 | Poldervaartite | Marsh R E (1994) A revised structure for alpha-dicalcium silicate hydrate Acta Crystallographica C50 996-997 |  | 1994 | synthetic Ca2SiO3OHOH | 0 | 293 |
| 0009148 | Poldervaartite | Heller L (1952) The structure of dicalcium silicate alpha-hydrate Acta Crystallographica 5 724-728 | | 1952 | synthetic Ca2SiO3OHOH | 0 | 293 |
| 0010286 | Poldervaartite | Yano T, Urabe K, Ikawa H, Teraushi T, Ishizawa N, Udagawa S (1993) Structure of alpha-dicalcium silicate hydrate Acta Crystallographica C49 1555-1559 | | 1993 | 0 | 293 | |
| 0001615 | Poldervaartite | Dai Y S, Harlow G E, McGhie A R (1993) Poldervaartite, Ca(Ca0.5Mn0.5)(SiO3OH)(OH), a new acid nesosilicate from the Kalahari manganese field, South Africa: Crystal structure and description American Mineralogist 78 1082-1087 |  | 1993 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.231 Å | (100) |
| 4.18 Å | (45) |
| 2.846 Å | (42) |
| 2.391 Å | (42) |
| 2.789 Å | (35) |
| 2.042 Å | (28) |
| 3.27 Å | (26) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) |
Geological Setting:
In massive manganese ore.
Type Occurrence of Poldervaartite
General Appearance of Type Material:
Colorless to milky white wheat-sheaf polycrystals and euhedral crystals.
Place of Conservation of Type Material:
American Museum Natural History, New York, USA, T100728
Geological Setting of Type Material:
Alteration of low-grade Mn-rich metasediments by hydrothermal fluids rich in Ca, Si02, and C02.
Associated Minerals at Type Locality:
Synonyms of Poldervaartite
Other Language Names for Poldervaartite
Relationship of Poldervaartite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 12 photos of Poldervaartite associated with Bultfonteinite | Ca2(HSiO4)F · H2O |
| 6 photos of Poldervaartite associated with Olmiite | CaMn2+[SiO3(OH)](OH) |
| 6 photos of Poldervaartite associated with Xonotlite | Ca6(Si6O17)(OH)2 |
| 2 photos of Poldervaartite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 1 photo of Poldervaartite associated with Manganvesuvianite | Ca19Mn3+Al4(Al6Mg2)(◻4)◻[Si2O7]4[(SiO4)10]O(OH)9 |
| 1 photo of Poldervaartite associated with Jennite | Ca9(Si3O9)2(OH)8 · 8H2O |
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF. | Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | 'Xenolite' | Al10Si8O31 |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.45 | Alleghanyite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.50 | 'Unnamed (Ca-analogue of Humite)' | Ca7(SiO4)4F2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.50 | 'Unnamed (OH-analogue of humite)' | Mg7(SiO4)3(OH)2 |
| 9.AF.50 | Fluorchegemite | Ca7(SiO4)3F2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Magnesiochloritoid | MgAl2O(SiO4)(OH)2 |
| 9.AF.85 | Ottrélite | Mn2+Al2O(SiO4)(OH)2 |
| 9.AF.85 | Chloritoid | Fe2+Al2O(SiO4)(OH)2 |
| 9.AF.90 | Olmiite | CaMn2+[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
Fluorescence of Poldervaartite
Deep red in SW
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Poldervaartite
mindat.org URL:
https://www.mindat.org/min-3252.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Poldervaartite
Reference List:
Dai, Yongshan, Harlow, George E., Mcghie, Andrew R. (1993) Poldervaartite, Ca(Ca0.5Mn0.5)(SiO3OH)(OH), a new acid nesosilicate from the Kalahari manganese field, South Africa: Crystal structure and description. American Mineralogist, 78 (9-10) 1082-1087
Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, G. I., 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 (2). 193-201 doi:10.1180/minmag.2007.071.2.193
Localities for Poldervaartite
Showing 4 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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).
All localities listed without proper references should be considered as questionable.
South Africa | |
| |
| Cairncross et al. (2002) +2 other references | |
| Dai et al. (1993) +3 other references |
Spain | |
| Dill et al. (2023) |
Quick NavTopAbout PoldervaartiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPronunciation Physical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Wessels Mine, Joe Morolong Local Municipality, John Taolo Gaetsewe District Municipality, Northern Cape, South Africa