Mining tech

[desperance]

I know two separate and unrelated words for the material, the unwanted base rock from which you dig your ore or precious stone or whatever it is you're mining for; and one of them is matrix and the other is gangue, and the first is too formal or technical or some such and the second is too obscure. Sigh. You'd think it would be easy, wouldn't you...? A language famous for its range of synonyms, an obvious and long-established need for a simple commonplace word, and I got nuthin'...