Qualactin

Qualactin was the only planet, apart from Bandraginus Five, on which the rare mineral Oolion occurred naturally. With the latter planet's destruction by the Captain, it became the only planet at all with Oolion deposits. (TV: The Pirate Planet)

Behind the scenes

 * The name of this planet was later referenced in Qualactin Hypermint Extract, an ingredient in the Pan Galactic Gargle Blaster from Douglas Adams' The Hitchhiker's Guide to the Galaxy series. The Pirate Planet was Douglas Adams' first contribution to Doctor Who.