Tallonian Crystal
From Star Trek : Freedom's Wiki
Tallonian Crystals are precious gemstones from the Tallonian homeworld.
They are illegal anywhere but on the Tallonian homeworld. To determine the purity of Tallonian crystals, a type 4 Tallonian microscanner is needed.
Quark tried to purchase Tallonian crystals from Regana Tosh but was apprehended by Odo. (DS9: "Hippocratic Oath")
The reason for their legal status is unknown.
