LIVE REPORT! Tucson 2019 - last updated 2 hours ago. Click here to watch.
Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat Articles
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery


This page is currently not sponsored. Click here to sponsor this page.
Hide all sections | Show all sections

About WindhoekiteHide

Ca2Fe3+2.67[Si8O20](OH)4 · 10H2O
Brown to yellowish brown
Vitreous, Silky
Specific Gravity:
Crystal System:
Named for the city of Windhoek, near the type locality.
Visually indistinguishable from tuperssuatsiaite.
Structurally related to tuperssuatsiaite and raite.

Classification of WindhoekiteHide

Approval Year:

9 : SILICATES (Germanates)
E : Phyllosilicates
E : Single tetrahedral nets of 6-membered rings connected by octahedral nets or octahedral bands

Pronounciation of WindhoekiteHide

PlayRecorded byCountry
Debbie WoolfUnited Kingdom

Physical Properties of WindhoekiteHide

Vitreous, Silky
Brown to yellowish brown
on {100}
2.62(2) g/cm3 (Measured)    2.630 g/cm3 (Calculated)

Optical Data of WindhoekiteHide

Biaxial (-)
RI values:
nα = 1.610(3) nβ = 1.662(3) nγ = 1.671(3)
Measured: 50° (10), Calculated: 44°
Max Birefringence:
δ = 0.061
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
None observed.
Brown to dark brown.

Chemical Properties of WindhoekiteHide

Ca2Fe3+2.67[Si8O20](OH)4 · 10H2O
IMA Formula:
Ca2Fe3+3-x[Si8O20](OH)4 · 10H2O

Crystallography of WindhoekiteHide

Crystal System:
Class (H-M):
2/m - Prismatic
Space Group:
C1 2/m 1
Cell Parameters:
a = 14.319(5) Å, b = 17.825(4) Å, c = 5.242(1) Å
β = 103.5(2)°
a:b:c = 0.803 : 1 : 0.294
Unit Cell V:
1301 ų

Epitaxial Relationships of WindhoekiteHide

Epitaxial Minerals:
Palygorskite(Mg,Al)5(Si,Al)8O20(OH)2 · 8H2O

X-Ray Powder DiffractionHide

Powder Diffraction Data:
11.04 (100)
4.432 (10)
4.134 (6)
3.749 (4)
3.486 (11)
2.636 (8)
2.550 (4)
2.507 (6)

Type Occurrence of WindhoekiteHide

General Appearance of Type Material:
Isolated long-prismatic crystals up to 0.15 mm across and 4 mm in length, and their radial aggregates up to 5 mm in size.
Place of Conservation of Type Material:
Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 4018/1.
Geological Setting of Type Material:
Hydrothermal mineral in miarolitic cavities of phonolite.
Associated Minerals at Type Locality:

Synonyms of WindhoekiteHide

Relationship of Windhoekite to other SpeciesHide

Other Members of this group:
Palygorskite(Mg,Al)5(Si,Al)8O20(OH)2 · 8H2OMon. 2/m : B2/m
TuperssuatsiaiteNa2Fe3Si8O20(OH)2 · 4H2OMon. 2/m : B2/m
Unnamed (Na-Ca-Fe-Silicate-Hydrate)NaCa(Fe2+,Al,Mn)5[Si8O19(OH)](OH)7 · 5H2OTric. 1 : P1
YofortieriteMn5Si8O20(OH)2 · 8-9H2OMon. 2/m : B2/m

Common AssociatesHide

Associated Minerals Based on Photo Data:
Neptunite1 photo of Windhoekite associated with Neptunite on

Related Minerals - Nickel-Strunz GroupingHide

9.EE.10BrokenhilliteMn8Si6O15(OH)10Hex. 6mm : P63mc
9.EE.10Pyrosmalite-(Fe)Fe2+8Si6O15(OH,Cl)10Trig. 3m (3 2/m) : P3m1
9.EE.10FriedeliteMn2+8Si6O15(OH,Cl)10Mon. 2/m : B2/m
9.EE.10Mcgillite(Mn,Fe)8Si6O15(OH)8Cl2Mon. 2/m : B2/m
9.EE.15SchalleriteMn2+16As3Si12O36(OH)17Trig. 3m : P3m1
9.EE.20Palygorskite(Mg,Al)5(Si,Al)8O20(OH)2 · 8H2OMon. 2/m : B2/m
9.EE.20TuperssuatsiaiteNa2Fe3Si8O20(OH)2 · 4H2OMon. 2/m : B2/m
9.EE.20YofortieriteMn5Si8O20(OH)2 · 8-9H2OMon. 2/m : B2/m
9.EE.25Falcondoite(Ni,Mg)4Si6O15(OH)2 · 6H2OOrth.
9.EE.25LoughliniteNa2Mg3Si6O16 · 8H2OOrth.
9.EE.25SepioliteMg4(Si6O15)(OH)2 · 6H2OOrth. mmm (2/m 2/m 2/m) : Pnna
9.EE.25Kalifersite(K,Na)5Fe3+7Si20O50(OH)6 · 12H2OTric.
9.EE.30GyroliteNaCa16Si23AlO60(OH)8 · 14H2OTric. 1 : P1
9.EE.30OrlymaniteCa4Mn3Si8O20(OH)6 · 2H2OHex.
9.EE.30TungusiteCa4Fe2Si6O15(OH)6Tric. 1 : P1
9.EE.35Reyerite(Na,K)2Ca14(Si,Al)24O58(OH)8 · 6H2OTrig.
9.EE.35Truscottite(Ca,Mn)14Si24O58(OH)8 · 2H2OTrig.
9.EE.45MakatiteNa2Si4O8(OH)2 · 4H2OMon. 2/m : P21/b
9.EE.50VarennesiteNa8Mn2Si10O25(OH,Cl)2 · 12H2OOrth.
9.EE.55RaiteNa4Mn2+3Ti0.25Si8O20(OH)2 · 10H2OOrth. 2 2 2 : C2 2 2
9.EE.60IntersiliteNa6Mn2+Ti[Si10O24(OH)](OH)3 · 4H2OMon.
9.EE.65ShafranovskiteNa3K2(Mn,Fe,Na)4[Si9(O,OH)27](OH)2 · nH2OTrig.
9.EE.65ZakharoviteNa4Mn5Si10O24(OH)6 · 6H2OTrig.
9.EE.70ZeophylliteCa13Si10O28(OH)2F8 · 6H2OTrig. 3 : R3
9.EE.80Fedorite(Na,K)2-3(Ca4Na3)Si16O38(OH,F)2 · 3.5H2OTric. 1 : P1
9.EE.80Martinite(Na,◻,Ca)12Ca4(Si,S,B)14B2O38(OH,Cl)2F2·4H2OTric. 1 : P1
9.EE.85Lalondeite(Na,Ca)6(Ca,Na)3Si16O38(F,OH)2·3H2OTric. 1 : P1

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 WindhoekiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Chukanov, N.V., Britvin, S.N., Blab, G., Belakovsky, D.I. and Van, K.V. (2011) Windhoekite, IMA 2010-083. CNMNC 2536 Newsletter No. 9, August 2011, page 2537; Mineralogical Magazine, 75, 2535-2540.
Rastsvetaeva, R.K., Aksenov, S. M. and Verin, I. A. (2012): Crystal structure of the NaCa(Fe2+,Al,Mn)5[Si8O19(OH)](OH)7•5H2O mineral: A new representative of the palygorskite group. Crystallography Reports 57, 43-48.
Chukanov, N.V., Britvin, S.N., Blass, G., Belakovskiy, D.I. & Van, K.V. (2012): Windhoekite, Ca2Fe3+3-x(Si8O20)(OH)4.10H2O, a new palygorskite-group mineral from the Aris phonolite, Namibia. European Journal of Mineralogy, 24, 171-179.

Internet Links for WindhoekiteHide

Localities for WindhoekiteHide

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.
Namibia (TL)
  • Khomas Region
    • Windhoek District
      • Aris
Chukanov, N.V., Britvin, S.N., Blab, G., Belakovsky, D.I. and Van, K.V. (2011) Windhoekite, IMA 2010-083. CNMNC 2536 Newsletter No. 9, August 2011, page 2537. Mineralogical Magazine, 75, 2535-2540; Chukanov, N. V.; Britvin, S. N.; Blass, G.; Belakovskiy, D. I.; Van, K. V. (2012): Windhoekite, Ca2Fe3+3-x(Si8O20)(OH)4•10H2O, a new palygorskite-group mineral from the Aris phonolite, Namibia. European Journal of Mineralogy 24, 171-179; Blass, G. & Tremmel, G. (2014): Neptunit und weitere neue Mineralien aus den Phonolith-Steinbrüchen von Aris, Windhoek. Mineralien-Welt 25 (1), 76-83 (in German).
Mineral and/or Locality is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Public Relations by Blytheweigh.
Copyright © and the Hudson Institute of Mineralogy 1993-2019, except where stated. relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: February 17, 2019 18:22:42 Page generated: February 4, 2019 07:13:04
Go to top of page