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Brownmillerite

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Formula:
Ca2(Al,Fe3+)2O5
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

Approved
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)
7.11.2.1

7 : MULTIPLE OXIDES
11 : Miscellaneous
7.20.15

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

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

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°
Max Birefringence:
δ = 0.080
Image 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:
Ca2(Al,Fe3+)2O5
Essential elements:
All elements listed in formula:

Relationship of Brownmillerite to other Species

Series:
Forms a series with Srebrodolskite (see here)
4.AC.05SwedenborgiteNaBe4Sb5+O7
4.AC.10SrebrodolskiteCa2Fe23+O5
4.AC.15MontroyditeHgO
4.AC.20LithargePbO
4.AC.20RomarchiteSnO
4.AC.25MassicotPbO
7.20.1WüstiteFeO
7.20.2MagnetiteFe2+Fe23+O4
7.20.3MaghemiteFe23+O3
7.20.4HematiteFe2O3
7.20.5Goethiteα-Fe3+O(OH)
7.20.6Akaganeiteβ-Fe3+O(OH,Cl)
7.20.7FeroxyhyteFe3+O(OH)
7.20.8Lepidocrociteγ-Fe3+O(OH)
7.20.9FerrihydriteFe103+O14(OH)2
7.20.10Amakinite(Fe2+,Mg)(OH)2
7.20.11MagnesioferriteMgFe23+O4
7.20.12MuskoxiteMg7Fe4O13 · 10H2O
7.20.13SrebrodolskiteCa2Fe23+O5
7.20.14HercyniteFe2+Al2O4

Other Names for Brownmillerite

Name in Other Languages:

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.

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

Localities for Brownmillerite

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 for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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
Galuskin, E., Galuskina, I., Kusz, J., Armbruster, T., Marzec, K., Dzierżanowski, P., Murashko, M. (2014): Vapnikite Ca3UO6 - a new double perovskite mineral from pyrometamorphic larnite rocks of the Jabel Harmun, Palestine Autonomy, Israel. Mineralogical Magazine, 78, 571-581
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
 
  • Brașov Co.
    • Racoş Commune
Szakáll, S., Kristály, F., 2010. Mineralogy of Székelyland, Eastern Transylvania, Romania. Sfântu Gheorghe-Miercurea Ciuc-Târgu Mureş. 2010.
  • 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.
Mineral and/or Locality  
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