Space: 1999 - Season 2 Episode 9 -

Alpha' s water system needs a rare mineral named Milgonite and scanners detect quantities of it on a barren planet the moon is passing. When Koenig leads a party to the planet to obtain the mineral, the Alphans discover that the rock structures on the planet are sentient and have a need for water, which they intend to take from the Alphans themselves!