blind
blind
o drill with the circulation medium (water or drill mud) escaping into the sidewalls of the borehole and not overflowing the collar of the drill hole.
An underground opening not connected with other workings nearby and at about the same elevation.
Said of a mineral deposit that does not crop out. The term is more appropriate for a deposit that terminates below the surface than for one that is simply hidden by unconsolidated surficial debris.