What is "mellite"

Mellite \Mel"lite\, n. [L. mel, mellis, honey: cf. F. mellite.] (Min.) A mineral of a honey color, found in brown coal, and partly the result of vegetable decomposition; honeystone. It is a mellitate of alumina.

n. (context mineralogy English) An mineral that is the aluminium salt of mellitic acid; honeystone

Mellite, also called honeystone, is an unusual mineral being also an organic chemical. Chemically identified as an aluminium salt of mellitic acid; that is, aluminium benzene hexacarboxylate hydrate, with the chemical formula AlC(COO)·16HO.

It is a translucent honey-coloured crystal which can be polished and faceted to form striking gemstones. It crystallizes in the tetragonal system and occurs both in good crystals and as formless masses. It is soft with a Mohs hardness of 2 to 2.5 and has a low specific gravity of 1.6.

It was discovered originally in 1789 at Artern in Thuringia in Germany it has subsequently also been found in Russia, Austria, the Czech Republic, and Hungary. It was named from the Greek μέλ˘ι, "melis" for honey, in allusion to its color.

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