In the Edith River area uranium occurs as meta-autunite associated with apatite and hematite in narrow siliceous reef formations which are in part brecciated and mylonized. The reefs, which dip steeply west and strike mostly north-north-west, occur over a length of about 3 miles in a north-south, sheared greisenized, zone in granite. Two main types of granite are present, a coarse grained granite and a finer-grained adamellite, which is intrusive into the coarse granite. In places partial digestion of the coarse by the fine granite has produced a porphyritic "hybrid" granite. All granites except the greisenized granite of the sheared zone give high background counts, 2 to 3 times as high as that of the sediments of the Brocks Creek group into which the coarse granite is intrusive. Within the reef formations the distribution of uranium-bearing material is patchy. In many places the best geiger readings are obtained where cross reefs or fractures with a north easterly strike cut the main reefs. Surface samples were taken across most places where significant Geiger readings were obtained and all returned less than .1% U3O8. Commercial production from the field will only be possible if the grade of the original ore has been greatly affected by surface leaching and a site was selected for a shaft to test the primary ore.
