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Unnamed (gamma-alumina)

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Crystal System:
A generally synthetic, gamma polymorph of alumina. It may, however, be an important constituent of some natural pyrometamorphic rocks (Ł. Kruszewski PXRD data, e.g. Ciesielczuk et al., 2015). It may also stand for a solid solution between Al2O3 and SiO2 known as "silicon spinel" (McHale et al., 1997). As such, it may be identical to 'Silicon Spinel'.

Paglia (2004) reports the following calcination pathway: gibbsite → böhmite → γ-Al2O3 → δ-Al2O3 (synthetic equivalent of deltalumite) → θ-Al2O3 (synthetic equivalent of UM1990-23-O:Al) → α-Al2O3 (corundum).

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Classification of Unnamed (gamma-alumina)Hide

Unnamed (probably invalid)

Chemical Properties of Unnamed (gamma-alumina)Hide


Crystallography of Unnamed (gamma-alumina)Hide

Crystal System:
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
spinel-type structure (e.g., Paglia, 2004)

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Unnamed (gamma-alumina)Hide

Reference List:
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Paglia, G. (2004): Determination of the Structure of γ-Alumina using Empirical and First Principles Calculations combined with Supporting Experiments. D.Ph. Thesis, Faculty of Science, Department of Applied Physics and Department of Applied Chemistry, Curtin University of Technology, 342 pp.
McHale, J.M., Yürekli, K., Dabbs, D.M., Navrotsky, A., Sundaresan, S., Aksay, I.A., (1997): Metastability of spinel-type solid solutions in the SiO2–Al2O3 system. Chemistry of Materials: 9: 3096–3100.
Ciesielczuk, J., Kruszewski, Ł., Majka, J. (2015): Comparative mineralogical study of thermally-altered coal-dump waste, natural rocks and the products of laboratory heating experiments. International Journal of Coal Geology: 139: 114-141.

Internet Links for Unnamed (gamma-alumina)Hide

Mineral and/or Locality  
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