Mellite, also called honeystone, is an unusual mineral being also an organic chemical.

[4] It is a translucent honey-coloured crystal which can be polished and faceted to form striking gemstones.

It was named from the Greek μέλι meli "honey",[5] in allusion to its color.

[3] It is found associated with lignite and is assumed to be formed from plant material with aluminium derived from clay.

[2] The crystal structure of mellite has been determined by neutron diffraction and consists of slightly distorted Al(H2O)63+ octahedra linked by hydrogen bonds to [C6(COO)6]6− mellitate anions and water of crystallization.