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This report describes a geophysical survey made in May 1952 and August 1953 at the Silver Valley mine workings, near Inverell, N.S.W. From the workings there is evidence of mineralisation along a well-defined fissure and one ore shoot has already been partly developed. The survey was made in an attempt to locate other ore shoots of sufficient size to warrant mining operations. Self-potential, magnetic and electromagnetic methods were used in the survey. The self-potential method showed a well-defined anomaly on the eastern extension of the fissure, indicating that a small body of sulphides may exist there with its centre about 300 feet east of the known ore shoot. The magnetic and electromagnetic results showed no pronounced anomalies which could be correlated with any defined ore shoot. Recommendations are made as to how the self-potential anomaly could best be tested. These comprise sinking a shaft at the centre of the anomaly, extending an existing adit, or driving a new adit from a point nearer the anomaly.

Geophysical surveys of the magnetite deposits of Australian Magnetite Pty. Ltd. at Gulgong were made by the Bureau in 1952 and 1953, and revealed that the Tallawang deposit was the most important one. The present report gives the results of a detailed magnetic survey which was made over this deposit in August, 1953. Results show that three concentrations of very strongly magnetic material exist within the Tallawang deposit. The southern concentration is unlikely to contain considerable reserves beyond those in sight. The central concentration has been partly worked and could yield reserves of ore from the west wall of the quarry. The northern concentration, which has not been worked, could yield limited reserves. It is shown that the deposit, as a whole, pitches northwards. Some exploratory drilling is recommended on each of the three concentrations.

On 28th September, 1954, West Australian Petroleum Pty. Ltd. forwarded a short length of core from a depth of about 3,880 feet in Cape Range Well No. 1. In hand specimen the rock is dark brownish grey in colour and is dense and tough. Fragments of wood and of a pelecypod shell are present. A micro-palaeontological examination of the rock yielded interesting information as to the age of the beds the well penetrated at this depth. This section of the rock and of the fragment of wood were cut, and portion of the rock was crushed in the hope of finding micro-fossils.

A car-borne radio-metric survey of the B-volcanic formation within the reservation surrounding the A.B.C. uranium prospect indicated 32 small areas in which the radio-activity was a little in excess of 1.5 times, and in places a little higher than twice the background count of the alluvium in the valley. Testing of each area with an Austronic P.R.M. 200 failed to reveal any sources of higher radio-activity. Most of the anomalies are due to a comparatively high background count given by exposed basalt. Four anomalies found in black or dark soil in damp portions of the valley are considered to be due to traces of radio-active elements absorbed by humus. One anomaly appeared to be due to traces of radio-active material contained in "lateritized" alluvium. The other anomalies are in alluvium, and are due either to the presence of basalt a few inches from the surface, or to traces of radio-active matter deposited from seeping ground-water. Radio-metric contouring, with a view to possible costeaning, has been recommended in a small area within exposed basalt, where counts of approximately 200 per minute were obtained. No additional work is recommended on any of the other anomalies.

This quarter, with its favourable climatic conditions, has seen the greatest activity in the field for the year. Thirteen geologists and five geophysicists, together with many assistants, have operated in the area on many prospects. The Darwin office and laboratory are well-established and providing many services to the public such as assaying, instrument repair, and geological and geophysical advice. Detailed geological and geophysical work has been commenced or continued at the following prospects: A.B.C., Edith River, Burrundie, Brock's Creek and Adelaide River, while minor investigations have been carried out at many other localities. Three drills have operated throughout the quarter. Regional geological mapping has been continued over a wide area. The amount of work being done will decrease during the coming quarter due to the approach of the "wet" season.

Self-potential and magnetic surveys made in the vicinity of the Mount Cleveland Tin Mine, near Waratah, Tasmania, are described and discussed. The first survey, which is described in Part I of this report, was made in April and May, 1953, at the request of the Department of Mines, Tasmania. The object of the survey was to ascertain whether geophysical methods could detect the known area of mineralisation and, if so, whether any additional areas of mineralisation could be discovered. Results of the first survey show that the geophysical anomalies, particularly the self-potential ones, coincide with the old mine workings. The anomalies over Luck's and Hall's workings, however, cover larger areas than the actual mine workings, thus indicating that further sulphide mineralisation may exist beyond these old workings. Anomalies not related to the old workings appear in an area north-west of Deep Creek, between traverses O and R. Both self-potential and magnetic methods revealed anomalies along these traverses between 350.E and 650.E, where geological investigation has also shown mineralisation to exist. Based on the results of the first survey, the grid was extended and surveyed to the north-east and south-west in March and April, 1954. This second survey, which is described in Part 2 of the report, shows that the anomaly connected with Henry's workings does not extend to the north-east, but terminates sharply between traverses P and Q. Some additional anomalies were recorded in the north-eastern extension of the grid, but in the south-western extension there was no geophysical evidence of mineralisation. It is suggested that further mining exploration work should be concentrated mainly near the former mine workings and in the area to the north-west of Deep Creek, between traverses O and R. Some prospecting trenches should also be put down to test the minor anomalies in the north-eastern part of the area.

In the course of geological investigation of the area included in the Katherine, Mt. Todd and Lewin Springs 1-miles sheets, carried out by J.H. Rattigan and A.B. Clark, Bureau of Mineral Resources, A.B. Clark found, in September 1953, uranium mineralization subsequently known as the A.B.C. Prospect, 11 miles north-north-east of the township of Katherine. This report is a record of the detailed investigation which followed the discovery.

The Ella Creek Prospect was a first order anomaly discovered by the Bureau of Mineral Resources airborne scintillometer survey in 1952. After a detailed examination by geologists and geophysicists, accompanied by intensive costeaning it was considered promising enough to warrant drilling. The three holes drilled were probed radio-metrically and high counts ranging from 1,000 to 3,000 per minute were obtained. No primary uranium mineralisation was encountered, and it is suggested that the source of the radioactivity, on chemical testing, may prove to be thorium.

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