Mines of Marlion
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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)