Chlormayenite
| Chlormayenite | |
|---|---|
| 240px
Crystal structure of chlormayenite (Cl− ions are omitted for clarity)[1]
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| General | |
| Category | Oxide mineral Mayenite supergroup |
| Formula (repeating unit) |
Ca12Al14O32[☐4Cl2] |
| Strunz classification | 04.CC.20 |
| Crystal symmetry | Isometric hextetrahedral H-M symbol: (43m) Space group: I43d |
| Unit cell | a = 11.98 Å; Z=2 |
| Identification | |
| Color | Colorless |
| Crystal habit | Microscopic anhedral grains |
| Crystal system | Cubic |
| Streak | White |
| Diaphaneity | Transparent |
| Specific gravity | 2.85 |
| Optical properties | Isotropic |
| Refractive index | 1.614–1.643 |
| Alters to | Absorbs water on exposure |
| References | [2][3][4] |
Chlormayenite (after Mayen, Germany), Ca12Al14O32[☐4Cl2], is a rare calcium aluminium oxide mineral of cubic symmetry.
It was originally reported from Eifel volcanic complex (Germany) in 1964. It is also found at pyrometamorphic sites such as in the Hatrurim Formation of Israel and in some burned coal dumps.[5][2]
It occurs in thermally altered limestone xenoliths within basalts in Mayen, Germany and Klöch, Styria, Austria. In the Hatrurim of Israel it occurs in thermally altered limestones. It occurs with calcite, ettringite, wollastonite, larnite, brownmillerite, gehlenite, diopside, pyrrhotite, grossular, spinel, afwillite, jennite, portlandite, jasmundite, melilite, kalsilite and corundum in the limestone xenoliths. In the Hatrurim it occurs with spurrite, larnite, grossite and brownmillerite.[2]
Synthetic Ca12Al14O33 and Ca12Al14O32(OH)2 are known, they are stabilized by moisture.[3][6] The formula can be written as [Ca12Al14O32]O,[7] which refers to the unique feature: anion diffusion process.[8]
Chlormayenite is also found as calcium aluminate in cement where its formula is also written as 11CaO·7 Al2O3·CaCl2, or C11A7CaCl2 in the cement chemist notation.
See also
References
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 Mayenite in the Handbook of Mineralogy
- ↑ 3.0 3.1 Chlormayenite. Mindat
- ↑ Mayenite. Webmineral
- ↑ Sokol E.V., Maksimova N.V., Nigmatulina E.N., Sharygin V.V. and Kalugin V.M. (2005) Combustion metamorphism, Novosibirsk: Publishing House of the SB RAS.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Boysen H., Kaiser-Bischoff I. and Lerch M. (2007) Anion Diffusion Processes in O- and N-Mayenite Investigated by Neutron Powder Diffraction. Bunsen Colloquium: Diffusion and Reactions in Advanced Materials (September 27th–28th, Clausthal-Zellerfeld, Germany) / The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and Application.
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