mullite
Sign in to saveMullite or porcelainite is a rare silicate mineral formed during contact metamorphism of clay minerals. It can form two stoichiometric forms: 3Al2O32SiO2 or 2Al2O3 SiO2. Unusually, mullite has no charge-balancing cations present. As a result, there are three different aluminium sites: two distorted tetrahedral and one octahedral.
Key facts
- Mineral.name
- Mullite
- Mineral.category
- Nesosilicate
- Mineral.image
- Osumilite, thick tabulars with Mullite - Ochtendung, Eifel, Germany.jpg
- Mineral.imagesize
- 260px
- Mineral.caption
- White, filamentous mullite in front of thicker osumilite platelets(Photo width 1.5 mm)Found in Wannenköpfe, Ochtendung, Eifel, Germany
- Mineral.formula
- Al6Si2O13
- Mineral.IMAsymbol
- Mul
- Mineral.strunz
- 9.AF.20
- Mineral.system
- Orthorhombic
- Mineral.class
- Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
- Mineral.symmetry
- Pbnm, Pnnm
- Mineral.unit cell
- a = 7.5785(6) Å, b = 7.6817(7) Å, c = 2.8864(3) Å; Z = 1
- Mineral.color
- Colorless to pale pink or grey
- Mineral.habit
- Prismatic to acicular crystals
- Mineral.cleavage
- Good on [010]
- Mineral.opticalprop
- Biaxial (+)
- Mineral.refractive
- nα = 1.642–1.653 nβ = 1.644–1.655 nγ = 1.654–1.679
- Mineral.birefringence
- δ = 0.012–0.026
via Wikipedia infobox
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Encyclopedic overview
4 sectionsContents
- Porcellanite
- Use in porcelain
- Use as a catalyst
- References
Mullite or porcelainite is a rare silicate mineral formed during contact metamorphism of clay minerals. It can form two stoichiometric forms: 3Al2O32SiO2 or 2Al2O3 SiO2. Unusually, mullite has no charge-balancing cations present. As a result, there are three different aluminium sites: two distorted tetrahedral and one octahedral.
Mullite was first described in 1924 for an occurrence on the Isle of Mull, Scotland. It occurs as argillaceous inclusions in volcanic rocks in the Isle of Mull, inclusions in sillimanite within a tonalite at Val Sissone, Italy and with emerylike rocks in Argyllshire, Scotland.
Excerpted from Wikipedia’s “mullite” article, available under the CC BY-SA 4.0 licence.
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