Vote for your favorite mineral in #MinCup26! - Azurite vs. Smithsonite
It's carbonate-vs-carbonate to kick off Mineral Cup 2026 with copper-rich Azurite against zinc-rich Smithsonite.
Log InRegister
Quick Links : The Mindat ManualThe Rock H. Currier Digital LibraryMindat Newsletter [Free Download]
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 ArticlesThe ElementsThe Rock H. Currier Digital LibraryGeologic TimeExplore Fossils
Minerals by PropertiesMinerals by ChemistryMineral Visual ExplorerAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsClubs & OrganizationsMineral Shows & EventsThe Mindat DirectoryDevice SettingsThe Mineral QuizTime Machine
Photo SearchPhoto GalleriesSearch by ColorPhoto Colour ExplorerNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography

Segelerite

A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
09112270017271926461846.jpg
Segelerite, etc.

Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA
05607510017271926531444.jpg
Segelerite, etc.

Mount Deverell variscite deposit, Milgun Station, Meekatharra Shire, Western Australia, Australia
04586460017271926567463.jpg
Segelerite

Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA
09112270017271926461846.jpg
Segelerite, etc.

Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA
05607510017271926531444.jpg
Segelerite, etc.

Mount Deverell variscite deposit, Milgun Station, Meekatharra Shire, Western Australia, Australia
04586460017271926567463.jpg
Segelerite

Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA
09112270017271926461846.jpg
Segelerite, etc.

Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA
05017650017271926635995.jpg
Segelerite, etc.

Mount Deverell variscite deposit, Milgun Station, Meekatharra Shire, Western Australia, Australia
Hide all sections | Show all sections

About SegeleriteHide

07025860017271926661003.jpg
Curt Segeler, ca1981
Formula:
Ca2 Mg2 Fe3+2(PO4)4(OH)2 · 8H2O
Colour:
Green, chartreuse, colorless, pale yellow
Lustre:
Vitreous
Hardness:
4
Specific Gravity:
2.67
Crystal System:
Orthorhombic
Member of:
Overite Group
Name:
Named for Curt G. Segeler (1901-1989), combustion atmosphere engineer for the America Gas Association. Curt invented the Degree Day rule of thumb used to estimate energy consumption for home heating. He was also an important amateur mineralogist, Brooklyn, New York, who specialized in phosphate minerals.
This page provides mineralogical data about Segelerite.


Unique IdentifiersHide

Mindat ID:
3605
Long-form identifier:
mindat:1:1:3605:0

IMA Classification of SegeleriteHide

Classification of SegeleriteHide

Strunz-mindat (2026):
8.DH.20

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
H : With large and medium-sized cations, (OH, etc.):RO4 < 1:1
Dana 8th ed.:
42.11.1.2

42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
Hey's CIM Ref.:
19.14.21

19 : Phosphates
14 : Phosphates of Fe and other metals

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference for Standard
SglIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Physical Properties of SegeleriteHide

Lustre:
Vitreous
Transparency:
Transparent, Translucent
Colour:
Green, chartreuse, colorless, pale yellow
Streak:
White
Hardness:
4 on Mohs scale
Hardness Data:
Measured
Cleavage:
Perfect
Perfect on the {010}
Density:
2.67 g/cm3 (Measured)    2.610 g/cm3 (Calculated)

Optical Data of SegeleriteHide

Type:
Biaxial (-)
RI values:
nα = 1.618 nβ = 1.635 nγ = 1.65
2V:
Measured: 45° to 70°, Calculated: 84°
Max. Birefringence:
δ = 0.032
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.

Surface Relief:
Moderate
Dispersion:
r > v
Pleochroism:
Visible
Comments:
X = Y = colorless; Z = yellow.
Comments:
Orientation: X = b; Y = a; Z = c.
Absorption: Z > X = Y.

Chemistry of SegeleriteHide

Mindat Formula:
Ca2 Mg2 Fe3+2(PO4)4(OH)2 · 8H2O
Element Weights:
Element% weight
O52.097 %
P15.516 %
Fe13.988 %
Ca10.039 %
Mg6.088 %
H2.272 %

Calculated from ideal end-member formula.
Elements listed:
Ca, Fe, H, Mg, O, P - search for minerals with similar chemistry

Crystallography of SegeleriteHide

Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pcca
Cell Parameters:
a = 14.826(5) Å, b = 18.751(4) Å, c = 7.307(1) Å
Ratio:
a:b:c = 0.791 : 1 : 0.39
Unit Cell V:
2,031.36 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Type material:
Long prismatic, striated parallel to the prism which is [001]. Nearly square outline, with lustrous {100}, {010}, {11O} and {121}.

Crystal StructureHide

Load
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
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File    Best | x | y | z | a | b | c
Rotation
Stop | Start
Labels
Console Off | On | Grey | Yellow
IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0000583SegeleriteMoore P B, Araki T (1977) Overite, segelerite, and jahnsite: a study in combinatorial polymorphism American Mineralogist 62 692-70219770293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.868 Å(100)
9.31 Å(90)
5.34 Å(60)
3.729 Å(50)
3.421 Å(50)
4.97 Å(40)
4.65 Å(40)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 7: Great Oxidation Event<2.4
47a : [Near-surface hydration of prior minerals]
Geological Setting:
National Museum of Natural History (Smithsonian), Washington, D.C., USA, 127154.

Type Occurrence of SegeleriteHide

Synonyms of SegeleriteHide

Other Language Names for SegeleriteHide

Relationship of Segelerite to other SpeciesHide

Member of:
Overite Group
Other Members of Overite Group:
Manganosegelerite(Mn2+,Ca)(Mn2+,Fe2+,Mg)Fe3+(PO4)2(OH) · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
OveriteCaMgAl(PO4)2(OH) · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
WilhelmvierlingiteCaMnFe3+(PO4)2(OH) · 2H2OOrth. mmm(2/m2/m2/m) : Pbca

Common AssociatesHide

Associations Based on Photo Data:
4 photos of Segelerite associated with LeucophosphiteKFe3+2(PO4)2(OH) · 2H2O
3 photos of Segelerite associated with RobertsiteCa2Mn3+3(PO4)3O2 · 3H2O
1 photo of Segelerite associated with NatrojarositeNaFe3(SO4)2(OH)6
1 photo of Segelerite associated with Jahnsite SubgroupXM1M22M32(H2O)8(OH)2(PO4)4
1 photo of Segelerite associated with MontgomeryiteCa4MgAl4(PO4)6(OH)4 · 12H2O
1 photo of Segelerite associated with HeterositeFe3+(PO4)

Related Minerals - Strunz-mindat GroupingHide

8.DH.Thebaite-(NH4)(NH4)3Al(C2O4)(PO3OH)2(H2O)Mon. 2/m : P21/b
8.DH.Whiteite-(MnMnMn)Mn2+Mn2+Mn2+2Al2(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.Ammoniotinsleyite(NH4)Al2(PO4)2(OH) · 2H2OMon. 2/m : P21/m
8.DH.Bergbauerite(H2O)2Mn2(Fe2Ti)(PO4)4(OH)2(H2O)10 · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.Dendoraite-(NH4)(NH4)2NaAl(C2O4)(PO3OH)2(H2O)2Mon. 2/m
8.DH.Rowleyite[Na(NH4,K)9Cl4][V5+,4+2(P,As)O8]6 · n[H2O,Na,NH4,K,Cl]Iso.
8.DH.HochleitneriteMn2Ti3(PO4)4O2(H2O)2 · 14H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.Whiteite-(CaMnFe)CaMnFe2Al2(PO4)4(OH)2 · 8H2OMon. 2/m
8.DH.05MinyuliteKAl2(PO4)2F · 4H2OOrth. mm2 : Pba2
8.DH.10LeucophosphiteKFe3+2(PO4)2(OH) · 2H2OMon. 2/m : P21/b
8.DH.10TinsleyiteKAl2(PO4)2(OH) · 2H2OMon.
8.DH.10Spheniscidite(NH4,K)(Fe3+,Al)2(PO4)2(OH) · 2H2OMon. 2/m
8.DH.15Jahnsite-(CaMnFe){Ca}{Mn2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(NaMnMn){Na}{Mn2+}{(Mn2+,Fe3+)2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(CaMnMg){Ca}{Mn2+}{(Mg,Fe2+)2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(CaMnMn){Ca}{Mn2+}{Mn2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Whiteite-(MnMnMg)MnMnMg2Al2(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(CaMnZn){Ca}{Mn2+}{Zn2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(MnMnMg){Mn2+}{Mn2+}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(MnMnFe){Mn2+}{Mn2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15'Jahnsite-(CaFeFe)'{Ca}{Fe2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon.
8.DH.15Rittmannite{(Mn2+,Ca)}{Mn2+}{(Fe2+,Mn2+,Mg)2}{(Al,Fe3+)2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15KeckiteCaMn2+(Fe3+Mn2+)Fe3+2(PO4)4(OH)3 · 7H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(NaMnMg){(Na,Ca)}{(Mn2+,Fe3+)}{(Mg,Fe3+)2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15'Jahnsite-(CaMgMg)'{Ca}{Mg}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2O
8.DH.15Jahnsite-(MnMnZn){Mn2+}{Mn2+}{Zn2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Whiteite-(CaMgMg)CaMg3Al2(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Whiteite-(CaFeMg){Ca}{(Fe2+,Mn2+)}{Mg2}{Al2}(PO4)4(OH)2 · 8H2OMon. 2/m : P21/b
8.DH.15Whiteite-(CaMnMg){Ca}{Mn2+}{Mg2}{Al2}(PO4)4(OH)2 · 8H2OMon. 2/m
8.DH.15Whiteite-(MnFeMg){(Mn2+,Ca)}{(Fe2+,Mn2+)}{Mg2}{Al2}(PO4)4(OH)2 · 8H2OMon. 2/m : P21/b
8.DH.15Jahnsite-(MnMnMn){Mn2+}{Mn2+}{Mn2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P21/b
8.DH.15'Kaluginite'(Mn2+,Ca)MgFe3+(PO4)2(OH) · 4H2OOrth.
8.DH.15Jahnsite-(CaFeMg){Ca}{Fe2+}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Whiteite-(CaMnMn){Ca}{Mn2+}{Mn2}{Al2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.15Jahnsite-(NaFeMg){Na}{Fe3+}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
8.DH.20Lun'okite(Mn,Ca)(Mg,Fe,Mn)Al(PO4)2OH · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.20Manganosegelerite(Mn2+,Ca)(Mn2+,Fe2+,Mg)Fe3+(PO4)2(OH) · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.20WilhelmvierlingiteCaMnFe3+(PO4)2(OH) · 2H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.20JuonniiteCaMgSc(PO4)2(OH) · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.20OveriteCaMgAl(PO4)2(OH) · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.25CalcioferriteCa4MgFe3+4(PO4)6(OH)4 · 12H2OMon. 2/m : B2/b
8.DH.25ZodaciteCa4Mn2+Fe3+4(PO4)6(OH)4 · 12H2OMon.
8.DH.25FanfaniiteCa4Mn2+Al4(PO4)6(OH)4 · 12H2OMon. 2/m : B2/b
8.DH.25KingsmountiteCa3Mn2+FeAl4(PO4)6(OH)4 · 12H2OTric. 1 : P1
8.DH.25MontgomeryiteCa4MgAl4(PO4)6(OH)4 · 12H2OMon. 2 : B2
8.DH.30PararobertsiteCa2Mn3+3(PO4)3O2 · 3H2OMon. 2/m : P21/b
8.DH.30RobertsiteCa2Mn3+3(PO4)3O2 · 3H2OMon. m : Bb
8.DH.30ArseniosideriteCa2Fe3+3(AsO4)3O2 · 3H2OMon. 2/m : B2/b
8.DH.30Sailaufite(Ca,Na,◻)2Mn3+3(AsO4)2(CO3)O2 · 3H2OMon. m : Bm
8.DH.30MitridatiteCa2Fe3+3(PO4)3O2 · 3H2OMon. 2/m : B2/b
8.DH.30KolfaniteCa2Fe3+3O2(AsO4)3 · 2H2OMon.
8.DH.35MantienneiteKMg2Al2Ti(PO4)4(OH)3 · 15H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.35Sperlingite (H2O)K(Mn2+Fe3+)(Al2Ti)(PO4)4[O(OH)] [(H2O)9(OH)] · 4H2OMon. 2/m : P21/b
8.DH.35PaulkerriteK(Mg,Mn2+)2(Fe3+,Al,Ti,Mg)2Ti(PO4)4(OH)3 · 15H2OMon. m
8.DH.35Hydroxylbenyacarite(H2O)2Mn2(Ti2Fe)(PO4)4[O(OH)](H2O)10 · 4H2O Orth. mmm(2/m2/m2/m) : Pbca
8.DH.35MacraeiteK(H2O)Mn2(Fe2Ti)(PO4)4[O(OH)](H2O)10 · 4H2OMon. 2/m : P21/b
8.DH.35Benyacarite(H2O)2Mn2Ti2Fe3+(PO4)4(OF)(H2O)10 · 4H2OOrth. mmm(2/m2/m2/m) : Pbca
8.DH.35Fluormacraeite [(H2O)K]Mn2(Fe2Ti)(PO4)4(OF)(H2O)10 · 4H2OMon. 2/m : P21/b
8.DH.40XanthoxeniteCa4Fe3+2(PO4)4(OH)2 · 3H2OTric. 1 : P1
8.DH.45MahnertiteNaCu3(AsO4)2Cl · 5H2OTet. 4/mmm(4/m2/m2/m) : I4/mmm
8.DH.50AndyrobertsiteKCdCu5(AsO4)4(H2AsO4) · 2H2OMon. 2/m : P21/m
8.DH.50CalcioandyrobertsiteKCaCu5(AsO4)4(H2AsO4) · 2H2OMon. 2/m : P21/m
8.DH.55EnglishiteK3Na2Ca10Al15(PO4)21(OH)7 · 26H2OMon. 2/m
8.DH.60BouazzeriteBi6(Mg,Co)11Fe3+14(AsO4)18(OH)4O12 · 86H2OMon. 2/m
8.DH.65GalliskiiteCa4Al2(PO4)2F8 · 5H2OTric. 1 : P1
8.DH.70JoteiteCa2CuAl(AsO4)[AsO3(OH)]2(OH)2 · 5H2OTric. 1 : P1
8.DH.75KampeliteBa6Mg3Sc8(PO4)12(OH)6 · 7H2OOrth. mmm(2/m2/m2/m) : Pnma
8.DH.80KapundaiteNaCaFe4(PO4)4(OH)3 · 5H2OTric. 1 : P1
8.DH.85VaniniiteCa2Mn2+3Mn3+2O2(AsO4)4 · 2H2OMon. 2/m : P21/b

Other InformationHide

Notes:
Soluble in dilute HCl.
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 SegeleriteHide

References for SegeleriteHide

Localities for SegeleriteHide

Showing 4 localities.

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.
Hide all sections | Show all sections

Locality ListHide

- 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). 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Australia
 
  • Western Australia
    • Meekatharra Shire
      • Milgun Station
Mineralogical Magazine 39 (1974)
Portugal
 
  • Viseu
Rend. Soc. It. Min. Petr.
      • Mangualde (Mesquitela e Cunha Alta)
Rewitzer et al. (1984)
USA (TL)
 
  • South Dakota
    • Custer County
      • Custer Mining District
        • Fourmile
Moore et al. (1974)
Quick NavTopAbout SegeleriteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
 
and/or  
Mindat.org® is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Mindat® and mindat.org® are registered trademarks of the Hudson Institute of Mineralogy.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
Content on this site may not be used to train, fine-tune, or otherwise develop artificial intelligence or machine learning models without prior written permission - see our Terms & Conditions.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833–844. doi:10.2138/am-2024-9486.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: September 1, 2026 05:54:06 Page updated: July 15, 2026 00:44:43
Go to top of page