Aluminium oxide (pronounced /ˌalumɪniʌm ˌɤksaid/) is the family of inorganic compounds with the chemical formula Al₂O₃. It is an amphoteric oxide and is commonly referred to as alumina, corundum as well as many other names, reflecting its widespread occurrence in nature and industry. Its most significant use is in the production of aluminium metal, although it is also used as an abrasive due to its hardness and as a refractory material due to its high melting point.

Aluminium oxide
Identifiers
CAS number	1344-28-1
PubChem	9989226
ChemSpider	8164808
UNII	LMI26O6933
RTECS number	BD120000
SMILES .... ....
InChI InChI=1S/2Al.3O/q2*+3;3*-2 Key: PNEYBMLMFCGWSK-UHFFFAOYSA-N InChI=1/2Al.3O/q2*+3;3*-2 Key: PNEYBMLMFCGWSK-UHFFFAOYAC
Properties
Molecular formula	Al2O3
Molar mass	101.96 g mol
Appearance	white solid very hygroscopic
Odor	odorless
Density	3.95-4.1 g/cm
Melting point	2072 °C
Boiling point	2977 °C
Solubility in water	insoluble
Solubility	insoluble in diethyl ether practically insoluble in ethanol
Refractive index (nD)	nω=1.768 - 1.772 nε=1.760 - 1.763 Birefringence 0.008
Structure
Crystal structure	Trigonal, hR30, SpaceGroup = R-3c, No. 167
Coordination geometry	octahedral
Thermochemistry
Std enthalpy of formation ΔfH298	−1675.7 kJ·mol
Standard molar entropy S298	50.92 J·mol·K
Hazards
MSDS	External MSDS
EU classification	Not listed.
NFPA 704	0 2 0
Flash point	non-flammable
Related compounds
Other anions	aluminium hydroxide
Other cations	boron trioxide gallium oxide indium oxide thallium oxide
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y(what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 Ã‚°C, 100 kPa)
Infobox references