- The principal ore of aluminum, composed mainly of hydrous aluminum oxides and aluminum hydroxides.
- A clay found at Les Baux, near Aries in France, and elsewhere, in concretionary grains or oölitic
- A ferruginous hydrate of alumina. It is the most commonly used ore for the preparation of aluminum and alumina. It is also used for the lining of furnaces which are exposed to intense heat.
- The <xref>principal</xref> <xref>ore</xref> of <xref>aluminium</xref>; a clay-like <xref>mineral</xref>, being a mixture of <xref>hydrated</xref> <xref>oxides</xref> and <xref>hydroxides</xref>.
- a clay-like mineral; the chief ore of aluminum; composed of aluminum oxides and aluminum hydroxides; used as an abrasive and catalyst