The Omarska deposit was originally comprised out of three ore bodies: Jezero, Buvac and a small ore body known as Mamuze. Ore reserves from Jezero and Mamuze have already been fully excavated. Since 2011, only the Buvac pit is in operation. It is formed within a carboniferous clastic and carbonate sediments. The genesis of this deposit is attributed to hydrothermal replacement and syn-sedimentary processes. The ore body is mainly composed of limonite-goethite mineralization, which was formed during weathering and oxidization of the primary siderite bodies. The Buvac deposit at Omarska mine is located within Carboniferous clastic (shale and sandstones) and carbonate (limestone, dolomite, and ankerite) sequences, with massive siderite-limonite mineralization forming an integral part of the formation. Iron ore from the Buvac deposit is predominantly limonite-goethite with associated quartz, carbonates, and silicates of the illite type. The limonite-goethite mineralization was formed during the oxidization of the upper parts of the primary siderite bodies. The ore body is asymmetrical, lens-shape and elongated in a northeast - southwest direction, dipping at about 8° toward the north-east from the surface to a depth of 210 meters. The deposit is approximately 1.5 kilometer long and 1.0 kilometer wide.

The Omarska mine is a production stage surface iron ore mine in Bosnia and Herzegovina. The ore is excavated from the Buvac deposit by traditional truck and shovel open pit mining methods. After a primary stage of crushing within the pit, the ore is transported to a processing plant via a conveyor.

The processing plant involves crushing, screening, gravity separation, magnetic separation and filtration. The plant is close to the mine site and crude ore is transported to the plant through a conveyor. Power is supplied from the national grid through a local power distribution company. The mine is in close proximity to public roads and a state railway, which is used for transporting the final product to the customer. Additionally, ArcelorMittal Prijedor operates a limestone quarry, from which the output is used for filling of the roads in the mine, as well as product for external customers.

The technology applied in the ore preparation is based on the gravitational and magnetic separation of limonite iron ore, featuring an average quality of 49.50% Fe, 12.50% SiO2 and 12% H2O. Further on, through crushing and multiple screening processes, followed by classifying on spiral classifiers and hydro-cyclones, and the treatment of fine fractions on high-intensity electromagneti ........