Red/red-brown crystals of brownmillerite from Caspar quarry, Bellerberg Volcano, Ettringen, Mayen, Eifel Mts, Rhineland-Palatinate, Germany
General
Category
Oxide mineral
Formula (repeating unit)
Ca2(Al,Fe)2O5
IMA symbol
Bmlr[1]
Strunz classification
4.AC.10
Dana classification
7.11.2.1
Crystal system
Orthorhombic
Crystal class
Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group
Ibm2
Unit cell
a = 5.57 Å, b = 14.52 Å, c = 5.34 Å; Z = 4
Identification
Color
Reddish brown
Crystal habit
As minute square platelets; massive
Diaphaneity
Semitransparent
Specific gravity
3.76
Optical properties
Biaxial (−)
Refractive index
nα = 1.960 nβ = 2.010 nγ = 2.040
Birefringence
δ = 0.080
Pleochroism
Distinct; X = Y = yellow-brown; Z = dark brown
2V angle
75° (measured)
References
[2][3][4][5]
Brownmillerite is a rare oxide mineral with chemical formula Ca2(Al,Fe)2O5. It is named for Lorrin Thomas Brownmiller (1902–1990), chief chemist of the Alpha Portland Cement Company, Easton, Pennsylvania.
Brownmillerite is a rare oxide mineral with chemical formula Ca2(Al,Fe)2O5. It is named for Lorrin Thomas Brownmiller (1902–1990), chief chemist of the...
orthorhombic, with density 3480 kg·m−3. The natural dicalcium aluminate, brownmillerite, may form at normal pressure but elevated temperature in pyrometamorphic...
in association with afwillite, calcite, larnite, spurrite, halite, brownmillerite, hydrocalumite, mayenite and ettringite. It was first described in 1933...
brownmillerite (4CaO·Al2O3·Fe2O3). The silicates are responsible for the cement's mechanical properties — the tricalcium aluminate and brownmillerite...
phosphate PO3− 4 in synthetic variants of the minerals apatite and brownmillerite. The manganate(V) anion was first reported in 1946 by Hermann Lux, who...
chondritic meteorites. Associated minerals in the Hatrurium include brownmillerite, mayenite and larnite. In meteorites it occurs with perovskite, melilite...
in the oxide notation. It also exists in nature as the rare mineral brownmillerite. In the absence of elements other than calcium, aluminium, iron and...
(redox reaction). Another materials suitable for PSA operation are brownmillerite-type materials such as La0.6Sr0.4Co0.2Fe0.8O3−d, La0.5Sr0.5Co0.5Fe0...
diffusion. Other promising materials include those with pyrochlore, brownmillerite, Ruddlesden-Popper, and orthorhombic K2NiF4-type structures. However...
wollastonite, garnet, anorthite, as well as rare minerals such as spurrite, brownmillerite, gehlenite, tacharanite, and larnite. These rare minerals only form...
Ca3TiFe(III)AlO8, is a mineral intermediate between perovskite (CaTiO3) and brownmillerite (Ca2(Fe,Al)2O5), a mineral of the cement clinker. Mindat location Weiss-Sarusi...
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