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Brownmillerite

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Formula:
Ca
 
2
(Al,Fe
3+
 
)
 
2
O
 
5
System:Orthorhombic
Name:The artificial compound was named in 1932 for Dr. Lorrin Thomas Brownmiller (1902-1990), Chief Chemist of the Alpha Portland Cement Company, Easton, Pennsylvania, USA. The name was then transferred to the naturally-occurring mineral.


Brownmillerite-Srebrodolskite Series.

Compare also the related species shulamitite.

Classification of Brownmillerite

IMA status:Approved
Strunz 8th edition ID:4/A.07-10
Nickel-Strunz 10th (pending) edition ID:4.AC.10

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
A : Metal: Oxygen = 2:1 and 1:1
C : M:O = 1:1 (and up to 1:1.25); with large cations (+- smaller ones)
Dana 8th edition ID:7.11.2.1

7 : MULTIPLE OXIDES
11 : Miscellaneous
Hey's CIM Ref.:7.20.15

7 : Oxides and Hydroxides
20 : Oxides of Fe
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Type Occurrence of Brownmillerite

Co-type Localities:Mayener Feld, Southern lava flow, Bellerberg volcano, Ettringen, Mayen, Eifel, Rhineland-Palatinate, Germany
Ettringer Feld, Western lava flow, Bellerberg volcano, Ettringen, Mayen, Eifel, Rhineland-Palatinate, Germany
Place of Conservation of Type Material:Mineral Museum, University of Cologne, Cologne, Germany (No. M5026/86)
National Museum of Natural History, Washington, D.C., USA (No. 120045)
Year of Discovery:1964
Geological Setting of type material:In thermally metamorphosed limestone blocks included in volcanic rocks
Associated Minerals at type locality:
WollastoniteSpinelPyrrhotitePortlanditeMayenite
LarniteJenniteJasmunditeGrossularGehlenite
EttringiteDiopsideCalciteAfwillite

Occurrences of Brownmillerite

Geological Setting:In thermally metamorphosed limestones

Crystallography of Brownmillerite

Crystal System:Orthorhombic
Class (H-M):mm2 - Pyramidal
Cell Parameters:a = 5.57Å, b = 14.52Å, c = 5.34Å
Ratio:a:b:c = 0.384 : 1 : 0.368
Unit Cell Volume:V 431.88 ų (Calculated from Unit Cell)
Z:2
Comment:Space group Ibm2. Other cell parameters given: a = 5.584(5), b = 14.60(1), c = 5.374(5) A.

Optical Data of Brownmillerite

Type:Biaxial (-)
RI values: nα = 1.960 nβ = 2.010 nγ = 2.040
2V:Measured: 75° , Calculated: 72°
Maximum Birefringence:δ = 0.080

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

Chemical Properties of Brownmillerite

Formula:
Ca
 
2
(Al,Fe
3+
 
)
 
2
O
 
5
Simplified for copy/paste:Ca2(Al,Fe3+)2O5
Essential elements:Al, Ca, O
All elements listed in formula:Al, Ca, Fe, O

Relationship of Brownmillerite to other Species

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

- +
4.AC.05Swedenborgite
NaBe
 
4
Sb
5+
 
O
 
7
4.AC.10Srebrodolskite
Ca
 
2
Fe
3+
2
O
 
5
4.AC.15Montroydite
HgO
4.AC.20Litharge
PbO
4.AC.20Romarchite
SnO
4.AC.25Massicot
PbO
Related Minerals - Hey's Index Grouping:

- +
7.20.1Wüstite
FeO
7.20.2Magnetite
Fe
2+
 
Fe
3+
2
O
 
4
7.20.3Maghemite
Fe
3+
2
O
 
3
7.20.4Hematite
Fe
 
2
O
 
3
7.20.5Goethite
α-Fe
3+
 
O(OH)
7.20.6Akaganeite
β-Fe
3+
 
O(OH,Cl)
7.20.7Feroxyhyte
Fe
3+
 
O(OH)
7.20.8Lepidocrocite
γ-Fe
3+
 
O(OH)
7.20.9Ferrihydrite
Fe
3+
5
O
 
3
(OH)
 
9
7.20.10Amakinite
(Fe
2+
 
,Mg)(OH)
 
2
7.20.11Magnesioferrite
MgFe
3+
2
O
 
4
7.20.12Muskoxite
Mg
 
7
Fe
 
4
O
 
13
· 10H
 
2
O
7.20.13Srebrodolskite
Ca
 
2
Fe
3+
2
O
 
5
7.20.14Hercynite
Fe
2+
 
Al
 
2
O
 
4

Other Names for Brownmillerite

Synonyms:
CeliteIMA1963-017
Other Languages:
German:Brownmillerit
Celit
Russian:Браунмиллерит
Spanish:Brownmillerita
Celita

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 Brownmillerite

Reference List:

- +
Hentschel, G., (1964): Mayenit, 12CaO 7Al2O3, und Brownmillerit, 2CaO.(Al,Fe)2O3, zwei neue Minerale in den Kalksteineinschlüssen der Lava des Ettringer Bellerberges: Neues Jahrb. Mineral., Mh. 1964, 22-29.

American Mineralogist: 50: 2106.

Acta Crystallographica: B27: 2311-2315.

Internet Links for Brownmillerite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Brownmillerite details from Handbook of Mineralogy (PDF)
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  • Localities for Brownmillerite

    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.
    Austria
     
    • Styria
      • Bad Radkersburg
        • Klöch
    R. Exel: Die Mineralien und Erzlagerstätten Österreichs (1993); Postl, W. et al. (2008)
    China
     
    • Xinjiang Autonomous Region
      • Hami Prefecture (Kumul Prefecture; Qumul Prefecture)
        • Hami Co. (Kumul Co.; Qumul Co.)
          • Huangshan-Jing'erquan ore belt
    Jingwen Mao, Pirajno, F., Zuoheng Zang, Fengmei Chai, Hua Wu, Shiping Chen, Linsong Cheng, Jianmin Yang, and Changqing Zhang (2007): Journal of Asian Earth Sciences (in press).
    Germany
     
    • North Rhine-Westphalia
      • Sauerland
        • Iserlohn
          • Letmathe
    Blaß, G. & Graf, H.W. (1994): Neufunde von bekannten Fundorten (IX). Mineralien-Welt, 5 (1), 18-21.
    • Rhineland-Palatinate
      • Eifel
        • Daun
          • Üdersdorf
    Schüller, W., Betz, V., Die Mineralien vom Emmelberg, Lapis 12/1986
        • Mayen
          • Ettringen
            • Bellerberg volcano
    Hentschel, G. (1978): Seltene Minerale in Calcium-reichen Auswürflingen vom Bellerberg bei Mayen/Eifel, Aufschluß 29, 77-83
              • Southern lava flow
    Hentschel, G. (1964): Mayenit, 12CaO . 7 Al2O3, und Brownmillerit, 2CaO.(Al,Fe)2O3, zwei neue Minerale in den Kalksteineinschlüssen der Lava des Ettringer Bellerberges, Neues Jahrbuch Mineralogie, Monatshefte, 22-29
              • Western lava flow
    Hentschel, G. (1964): Mayenit, 12CaO . 7 Al2O3, und Brownmillerit, 2CaO.(Al,Fe)2O3, zwei neue Minerale in den Kalksteineinschlüssen der Lava des Ettringer Bellerberges, Neues Jahrbuch Mineralogie, Monatshefte, 22-29
    Israel
     
    • Negev
    Sharygin, V.V., Sokol, E.V. & Vapnik, Ye. (2008): Minerals of the pseudobinary perovskite-brownmillerite series from combustion metamorphic larnite rocks of the Hatrurim Formation (Israel). Russian Geology and Geophysics 49, 709-726.
    Gross, S. (1977): The Mineralogy of the Hatrurim Formation, Israel. Geological Survey of Israel, Bulletin no. 70, 80 pp.
    Palestine
     
    • West Bank
      • Hatrurim formation
    Mikhail N. Murashko analytical data
    Ella V. Sokol, Olga L. Gaskova, Svetlana N. Kokh, Olga A. Kozmenko, Yuri V. Seryotkin, Yevgeny Vapnik, and Michail N. Murashko (2011): Chromatite and its Cr3+- and Cr6+-bearing precursor minerals from the Nabi Musa Mottled Zone complex, Judean Desert. American Mineralogist, 96, 659-674.
    Romania
     
    • Harghita Co.
      • Odorheiu Secuiesc (Székelyudvarhely; Oderhellen)
        • Racoş (Racoşu de Jos)
    Szakáll, S. & Kristály, F., Eds. (2010): Mineralogy of Székelyland, Eastern Transylvania, Romania. Csík County Nature and Conservation Society, Miercurea-Ciuc, Romania, 321 pp.
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    Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. 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 thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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