Tallonian crystal

Tallonian crystals are a type of gemstone found on the Tallonian homeworld. It is illegal to transport Tallonian crystals off their native planet.

Quark attempted to purchase Tallonian crystals in 2373, but was stopped from doing so by Odo. 

In an alternate timeline, Nancy Hedford negotiated with the black marketeers on Epsilon Canaris III, striking a bargain that made numerous alien goods, such as Tallonian crystals, legal to trade in United Earth territory.