Definition

Noun: 1. A chemical compound: Aluminum oxide is a compound consisting of aluminum and oxygen with the chemical formula Al₂O₃. It occurs naturally in various crystalline forms. 2. A mineralogical term: It refers to the naturally occurring mineral forms of this compound, most notably corundum, which includes gem varieties like ruby and sapphire.

Usage Examples

• The abrasive properties of aluminum oxide make it useful for sandpaper.
• Aluminum oxide is the primary component of the mineral corundum.
• This ceramic is made from a fine powder of aluminum oxide.

Advanced Usage

• In materials science: Aluminum oxide is often referred to as alumina, especially in industrial and ceramic contexts. It is valued for its hardness, high melting point, and electrical insulation properties.
  • The substrate for the microchip is made from high-purity alumina.
• In gemology: Specific colored varieties of crystalline aluminum oxide (corundum) have distinct names.
  • Ruby is red aluminum oxide colored by chromium impurities.

Variants and Related Words

• Alumina (n): The most common name for aluminum oxide, especially in industrial, materials science, and chemical contexts.
• Corundum (n): The natural crystalline mineral form of aluminum oxide. Sapphire and ruby are gem-quality corundum.
• Sapphire (n): A gemstone variety of corundum (aluminum oxide) that is typically blue, but can be other colors except red.
• Ruby (n): A red gemstone variety of corundum (aluminum oxide).

Synonyms

• Alumina
• Corundum (when referring to the specific mineral)

Notes on Different Meanings

The term "aluminum oxide" consistently refers to the chemical compound Al₂O₃. Its different meanings or applications stem from its various physical forms (e.g., powdered abrasive, synthetic single crystal, natural gemstone) and the contexts in which it is used (chemistry, industry, gemology).

Noun

1. any of various forms of aluminum oxide occurring naturally as corundum