Very uncommon, this is a large and fine crystal of the unique, organic-based mineral Mellite, most of which come from Hungary. This is an Aluminum mellitate (benzene hexacarboxylate) hydrate, a rare secondary mineral in lignite deposits. You simply do not see these for sale often, and they have been found in only nine localities worldwide. The medium-brown crystals here are gemmy to translucent, with excellent luster and sharp form. Superb for what they are, and seldom seen for sale. This piece in particular has higher luster than normal.