Mines of Marlion

This topic might have a better name.

Surely Diamond Mines of Marlion is the name given in these sources.

Talk about it here.

The Diamond Mines of Marlion were noted in Reginald Tyler's The True History of Planets. (PROSE: Mad Dogs and Englishmen)

Iris Wildthyme and Jenny Winterleaf once helped the Second Doctor defeat the Dalek Supreme in the Diamond Mines of Marlion. (PROSE: Bafflement and Devotion) In either the same adventure or a separate occasion, Iris stole a damaged Memory Crystal from the mines gift shop after knocking down the shop display. (AUDIO: Wildthyme at Large)

They had a unique currency of diamonds. (PROSE: The Panda Book of Horror)