When comparing the data of exploration and operation at the sites of the Sarbaisky and Sokolovskoye open pits, it was found that operational exploration on a grid of 50x25 m does little to refine the data of detailed exploration carried out on a grid of 100x50 m. At the same time, at the sites of both open pits, in detailed and operational exploration, ore reserves and the iron content in them are slightly underestimated.