A quarry was an open pit dug into the surface of a planet, for the purpose of mining substances perceived to be valuable. They were distinct from underground mine shafts — such as those which existed on the planet Peladon, (TV: The Monster of Peladon) or those exploited on the planet Ta by Milo Clancey and Dom Issigri. (TV: The Space Pirates)
Humans on Earth in the 20th century frequently used quarries. The Fourth Doctor, in the company of Sarah Jane Smith, landed in a quarry. There, blasting work was being carried out and both the time travellers were caught in the debris. While trapped under some rock, Sarah found the hand of Eldrad, which had been encased in dolomite for one hundred and fifty million years. (TV: The Hand of Fear)
Behind the scenes
Quarries have frequently been used throughout Doctor Who's filming history to suggest alien landscapes. So ubiquitous were they in the 1963 version of the show, in particular, that they became a point of parody, for instance, in The Curse of Fatal Death.