I RECENTLY TASTED a bottle of Chablis described by its accompanying fact sheet as "delicate, rich, rather mineral and dry." I understood the meaning of each adjective—except for one. What exactly is a "mineral" wine, let alone a "rather mineral" one?

While "minerality" has long been employed as a wine descriptor, it has only recently become quite popular. "It's a word everyone's using for everything," said Chablis producer Fabien Moreau, who started seeing its use rise around...