Since 1949 a considerable amount of geological and geophysical investigation as well as diamond drilling and some underground development has been undertaken in the search for uranium ore in the Darwin-Katherine region, and in the course of this work information has been gained which, it is thought, may be of interest to prospectors and companies who are now beginning to pay considerable attention to the possibilities of the area, but have had little or no experience of prospecting for uranium in the Katherine-Darwin region. Investigations of the area by the Bureau, by private companies, and by prospectors [are] now proceeding more vigorously than ever, and without doubt a good deal more remains to be found out concerning the uranium deposits of this province. In these circumstances the notes supplied below are put forward tentatively as being some facts known to the present writer at this time (July, 1953) as well as some more controversial opinions. It is expected that more information will be made available as the investigation proceeds. (The following notes should be read in conjunction with Pamphlet No. 3 (Radioactive Mineral Deposits) of the Bureau of Mineral Resources, Geology and Geophysics and a copy of the Mineral Map (NT32B-4) would greatly aid in their understanding).

The air-borne scintillometer survey near Katherine during October, 1953, failed to cover a triangular area in the south-east corner of the Katherine sheet, as it was beyond the range of the Shoran beacons. The area is part of a Bureau of Mineral Resources reservation taken out to protect the ABC Prospect. Several trial flights were made over the area, however, in an attempt to detect the presence of any significant radiometric anomalies. During these flights, Geologist A.B. Clark acted as an observer to spot on photo-mosaics the positions at which anomalies might occur. A third order anomaly was recorded during a flight along Maude Creek at a point thought to be within 1 mile of the junction of Dorothy Creek and Maude Creek. A search was made later by D.E. Gardner with the object of finding the source of the anomaly and the results of this work are given below.

The areas included in the geophysical survey, namely the Laloki, Moresby-King and Dubuna leases, are among those held by Mandated Alluvials N.L., and lie in the Astrolabe Mineral Field. The positions of the leases held by the Company are shown in Plate G73-1. Laloki, the main producer of copper, is situated 20 miles by road from Port Moresby, near the junction of Sapphire Creek with the Laloki River. The Bureau was requested by Mandated Alluvials to carry out a geophysical survey in the vicinity of the known deposits and in adjacent areas. Both Laloki and Moresby-King mines has been in production up to the time when the war in New Guinea caused a suspension of operations. During the war the mine workings and much of the plant were completely destroyed. When consideration was given to the best method of reopening the mines it was decided that, if a large enough tonnage or ore could be proved sufficiently close to the surface, it would be most profitable to continue open-cut mining, and possibly install a flotation concentrator to avoid the troubles that had always accompanied smelting. The aim of the geophysical survey was, therefore, to locate a body of ore large enough to justify the adoption of these mining and treatment methods.

Operations of the Radioactive Section have been restricted during this quarter due to the "wet" season and lack of staff. Drilling operations at the Ella Creek Prospect were completed and operations commenced at the Edith River Prospect. No encouraging results were disclosed at either prospect. Other work has been limited to inspection of reported new discoveries and geophysical work in the Rum Jungle area.

Report on the activities of the administrative and technical sections in the Katherine-Darwin area, to April, 1954. A brief account is given of geological and geophysical operations. The results of prospecting and field work are summarised.

The prospect covers an area originally enclosing three first order and one second order anomaly located by the Airborne Scintillometer Survey if 1952. Preliminary ground investigation was carried out in October 1952 and is contained in 'Preliminary Report on Airborne Scintillometer Surveys by N.H. Fisher and J. Sleiss'. Carborne equipment was first used to locate the anomalies and determine their extent in July, 1953. An Auster aircraft carrying a Halross scintillometer also flew over the area at the same time locating a high only near the first zone. This was carried out by the Territory Enterprise Limited. A survey grid was laid down to serve both the geological and geophysical work. The base line runs north-south for 3,300 feet and traverse lines run across it at 100 ft. intervals. The detailed radioactive survey covered the whole area. Traverse lines were read at 300 foot intervals in the outer sections where closer work was not warranted. The work commenced in August and was completed in October 1953.

Report on the activities of the administrative and technical sections in the Katherine-Darwin area, to October, 1954. A brief account is given of geological and geophysical operations. The results of prospecting and development work are summarised.

High Geiger readings in the vicinity of the Number 1 prospect were first obtained by Sidney Fabian (a prospector for Northern Uranium Development) who drew my attention to this fact and showed me the area on Sunday 14th November, 1954. No detailed work was done. The area was re-visited by the author on Tuesday, 23rd November, 1954. It was on this date that the region of radio-activity and the rock responsible for it were established. The Number 2 prospect was discovered independently by the author on Tuesday 23rd November, 1954, while prospecting along the line of the South Alligator Fault Zone.

Mt. Fitch Prospect is situated five miles on a bearing of N30°W from Rum Jungle siding. It was first visited in October 1949 by [an] officer of the Bureau (Ward, 1950). During 1950 Geologists Ward and Gates discovered the presence of yellow secondary uranium minerals in limestone. Radio-metric contouring and geological mapping was undertaken in May 1950 and a plan was produced on a scale of 100 feet to an inch. In 1950 a plan of the workings was produced on a scale of 40 feet to an inch and an aerial photograph enlarged to a scale of approximately 400 feet to an inch was used to map the Mt. Fitch area. The limited amount of prospecting work at Mt. Fitch has as yet not indicated the presence of an important uranium ore body in the area but further testing is warranted. The area of radioactivity is adjacent to the limestone slate contact and is similar in this respect to Brown's Deposit, (Ward, 1953).

Brown's Deposit is the westernmost known area of mineralization in the Rum Jungle area. It is situated approximately two miles northeast of Rum Jungle Railway Siding and one mile southwest of White's Deposit in an area known as Brown's Workings, which was worked for copper in the early part of the century. In June 1950, preliminary geophysical investigations revealed that a radiometric anomaly was present at the eastern end of the old copper workings, and in October 1940, a self-potential survey (Allen 1950) indicated the presence of two distinct bodies of sulphide mineralization. During 1950 a geological map of the area on a scale of 100 feet to an inch was prepared, and in 1951 mapping of the area on a scale of 40 feet and 20 feet to an inch was commenced. This work at present remains unfinished due to other commitments. Three diamond drill holes, part of an extensive programme of diamond drilling planned for the area were drilled towards the end of 1951.