Mining Iron Ore Mining iron ore begins at ground level. Taconite is identified by diamond drilling core samples on a grid hundreds of feet into the earth. Taconite rock comprises about 28 percent iron; the rest is sand or silica. These samples are analyzed and categorized so that mining engineers can accurately develop a mine plan.
Mineral Sands. The grade from a typical mineral sand deposit is low – most ore deposits will have a total heavy mineral (THM) concentrate from the bulk sand of around 1% heavy minerals although some deposits can be significantly higher than this.