The Minorca deposits are examples of Superior-type BIF deposits, specifically the Biwabik Iron Formation (Biwabik IF), which is interpreted to have been deposited in a shallow, tidal marine setting and is characterized as having four main members (from bottom to top): Lower Cherty, Lower Slaty, Upper Cherty, and Upper Slaty. Cherty units generally have a sandy granular texture, are thickly bedded, and are composed of silica and iron oxide minerals. Slaty units are fine grained, thinly bedded, and comprised of iron silicates and iron carbonates, with local chert beds, and they are typically uneconomic. The mineral of economic interest at Minorca is magnetite.

The Biwabik IF at Minorca consists primarily of carbonates, iron silicates, fine-grained quartz, and iron oxides. These layers are visually distinct, locally separated into slaty beds and cherty beds. The ratio of slaty to cherty beds and distance between these beds are key indicators used during logging, as well as bedding style, texture, color, and magnetic strength. Slaty beds are dark gray in nature, consisting primarily of magnetite in mineralized zones, and range from one millimeter (0.04 in.) to upwards of two centimeters (0.78 in.) in thickness. Cherty beds range from gray to green in color depending on the ratio of fine-grained quartz (gray color) to iron silicates (green color). These beds vary in thickness to upwards of 10 cm (3.9 in.) and may or may not contain disseminated magnetite. Carbonates ty ........

The Laurentian, East 1, and East 2 areas are mined using conventional surface mining methods. The surface operations include:
• Clearing and grubbing;
• Overburden (glacial till) removal;
• Drilling and blasting (excluding overburden);
• Loading and haulage.

The open-pit operation at Minorca has a mining rate of approximately 8.6 million long tons (MLT) of ore per year and produces 2.8 MLT of wet flux iron ore pellets.

The current LOM plan has mining for 14 years and mines the known Mineral Reserve. The average stripping ratio is 0.8 waste units to 1 crude ore unit (0.8 stripping ratio).

The final Laurentian Pit is approximately 1.2 mi long along strike, 0.9 mi wide, and up to 640 ft deep. Crude ore averages approximately 24.4% MagFe. The final East 1 Pit is approximately 0.9 mi along strike, 0.5 mi wide, and up to 310 ft deep. Crude ore within the East 1 Pit averages approximately 22.5% MagFe. The East 2 final pit is approximately 0.7 mi along strike, 0.4 mi wide, and up to 350 ft deep. The East 2 Pit crude ore contains an average of 23.7% MagFe.

Primary production for all mine pits includes drilling a combination of 12.25 in.- and 16.00 in.-diameter rotary blast holes. Production blast hole depth varies as the pit benches transition from the footwall contact to a full 35 ft bench height. Burden and spacing varies depending on the material being drilled. The holes are filled with explosive and blasted. A comb ........

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