Silicon Spinel
Invalid as an unnamed mineral
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Formula:
2Al2O3 · 3SiO2
or possibly spinel-structured γ-Al2O3 that is better written as Al2.67◻0.33O4.
May also be formulated as Al4Si3O12
May also be formulated as Al4Si3O12
A phase (synthetic) known to be formed due to thermal transformation of kaolinite adn illite, e.g. in coal combustion. May be formed from thermal destruction of 'meta-kaolinite' or 'meta-illite' at 900oC. At 950oC it transforms to 'pseudomullite'.
In the presence of CaO it transforms to anorthite and 'pseudomullite', at 850-1100oC. When the content of available CaO is larger, the product (at 950-1100oC) is gehlenite. It may also be a precursor to esseneite, if considerable amount of Fe2O3, CaO, and SiO2 is present in the environment and the temperature is 950-1100oC (Querol et al., 1994).
It is quite likely, that this phase corresponds to γ-alumina (Unnamed (gamma-alumina)). According to Sun et al. (2006), the spinel-type structure is attributable to this form of Al2O3 instead of non-spinel ones. Also, Ward (2002) reports (cites) that 'meta-kaolinite' transforms to γ-alumina, mullite and cristobalite at 950-1000oC, which somehow fits to the aforementioned processes.
It seems possible, that this phase exists in natural pyrometamorphic zones.
In the presence of CaO it transforms to anorthite and 'pseudomullite', at 850-1100oC. When the content of available CaO is larger, the product (at 950-1100oC) is gehlenite. It may also be a precursor to esseneite, if considerable amount of Fe2O3, CaO, and SiO2 is present in the environment and the temperature is 950-1100oC (Querol et al., 1994).
It is quite likely, that this phase corresponds to γ-alumina (Unnamed (gamma-alumina)). According to Sun et al. (2006), the spinel-type structure is attributable to this form of Al2O3 instead of non-spinel ones. Also, Ward (2002) reports (cites) that 'meta-kaolinite' transforms to γ-alumina, mullite and cristobalite at 950-1000oC, which somehow fits to the aforementioned processes.
It seems possible, that this phase exists in natural pyrometamorphic zones.
Unique Identifiers
Mindat ID:
51665
Long-form identifier:
mindat:1:1:51665:9
IMA Classification of Silicon Spinel
IMA status notes:
Unnamed (probably invalid)
Pronunciation of Silicon Spinel
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Chemistry of Silicon Spinel
Mindat Formula:
2Al2O3 · 3SiO2
or possibly spinel-structured γ-Al2O3 that is better written as Al2.67◻0.33O4.
May also be formulated as Al4Si3O12
or possibly spinel-structured γ-Al2O3 that is better written as Al2.67◻0.33O4.
May also be formulated as Al4Si3O12
Element Weights:
Elements listed:
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.
Internet Links for Silicon Spinel
mindat.org URL:
https://www.mindat.org/min-51665.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Silicon Spinel
Localities for Silicon Spinel
Showing 1 localities.
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The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Poland | |
| Ł. Kruszewski EPMA data |
