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|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.|
Classification of Brownmillerite
|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:||188.8.131.52|
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:|
Occurrences of Brownmillerite
|Geological Setting:||In thermally metamorphosed limestones|
Crystallography of Brownmillerite
|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 Å³ (Calculated from Unit Cell)|
|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
|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|
Chemical Properties of Brownmillerite
|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):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Brownmillerite
|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
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
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.
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New Locality Added: White Swan Mine, Pretoria, Gauteng Province, South AfricaFrom Debbie Woolf, 7th Dec 2013 01:35:51