The Ranger No. 1 and No. 3 orebodies contain about 124,000 tonnes l^Og in highly chloritized metasediments of the lower Proterozoic Cahill Formation within about 500 m of the projected sub-Kombolgie Formation unconformity. In both orebodies, oxidized and reduced uranium minerals occur chiefly in quartzose schists that have highly variable amounts of muscovite, sericite, and chlorite.

Below the oxidized zone, uranium occurs chiefly as uraninite and pitchblende disseminated through thick sections of quartz-chlorite-muscovite schist and has no apparent association with graphite or sulfides. In fact, graphite is rare and sulfides are generally low in abundance (<0.5 percent). Higher ore grades occur in disrupted zones a few centimeters thick and in some quartz chlorite vein-like zones of uncertain origin. Uranium correlates strongly with chlorite, but not all of the many ages of chlorite have associated uranium. At least five textural varieties of chlorite are present and represent at least 3 ages. Preliminary microprobe analyses suggest that Mg-Fe-Al contents are relatively uniform. Apatite commonly occurs with chlorite. Uranium is not common in carbonate rocks and seems to occur only in disrupted zones that have chlorite alteration.

The structure of the orebodies is outwardly simple, particularly in No. 3; dips are less than 40° on most lithologic contacts. The No. 1 orebody is in a basin-like structure about 400 m wide that probably formed in part by progressive removal of carbonate rocks that are as much as 200 m thick adjacent to the No. 1 orebody and below the No. 3 orebody. Quartz-chlorite breccias have formed in the zone of carbonate thinning; uranium is spotty and low grade in these breccias. Chloritized and uraniferous broken and sheared zones, a few centimeters to a few meters thick, have an unknown attitude but must have small displacement. Blocks of altered Kombolgie sandstone are downfaulted into the No. 3 orebody and locally contain reduced uranium minerals. One or more shear zones 5-30 m thick.

Ranger is a large unconformity-related deposit and the ore is mined by open cut methods. As depicted in figure 3.3, within the Ranger Project there are two orebodies—Ranger No. 1 (now mined out) and Ranger No. 3 which is currently being mined. Open cut mining at the Ranger No. 1 orebody began in August 1981 and was completed by December 1994. Production from the processing plant continued from stockpiled ore until open cut mining commenced at Ranger No. 3 orebody in October 1996.

The mill uses a sulphuric acid leach process to dissolve uranium from the ore. Uranium is recovered from the leachate by solvent extraction and is precipitated as ammonium diuranate (yellowcake). This is then calcined (heated to more than 200°C to remove volatile components) to produce concentrates of uranium oxide (greygreen coloured powder) assaying 99.2 per cent U3O8.