In January, 1951, samples of radioactive minerals stated to have been collected in the Mt. Kavanagh (Cavenagh) area, Central Australia, were submitted to the Bureau by Mr. Norman Ashmore. Two radioactive minerals were present, one apparently allanite, and the other a strongly radioactive mineral of composition similar to betafite. The opportunity was taken of the presence in Alice Springs of the geophysical party destined for Rum Jungle and the geological party destined for Maranboy to make a brief inspection of the area. Two days were spent in the area. This report gives an account of the investigations and their results.

In the search for deposits of radioactive minerals in Australia the area of the Barrier Ranges appears especially worthy of investigation on geological grounds because it is composed of highly mineralised pre-Cambrian rocks. Mines in this area comprise the major producing mines along the main Broken Hill lode, one developed mine of less importance (the Pinnacles), and a number of small silver, lead and copper mines scattered over the surrounding district. The present report deals with the results of a reconnaissance radio-active survey performed by the Geophysical Section of the Bureau during July and August, 1950. The work was confined to the smaller mines, attention being directed, in the first instance to the mines from which radio-active museum specimens were stated to have come. At each mine the following tests were performed: tests on dumps and residues to discover whether any quantity of stone carrying a significant content of radio-active minerals had been broken during mining operations, tests on accessible exposed faces, and tests on rocks surrounding the mines. The tests were made with portable Geiger-Mueller rate-meters. Readings taken are quoted as multiples of background count, which has been considered as a constant characteristic of the instruments, rather than as the general reading obtained on country rock in the area. In most areas these methods of defining background would lead to the same result. As mentioned later, however, in the Broken Hill area this is not the case. Generally, the schists and gneisses on this field are definitely radio-active, and a true background reading, indicative of the complete absence of radio-active minerals, is obtained only on basic rocks. A reconnaissance survey was also made over the Euriowie tin field. Tests were also made around felspar quarries at Egebeck.

This statement gives the results of a scout drilling campaign conducted by the Bureau at the Kirby's Hill Area of the Western Coalfield of New South Wales. The area investigated comprises approximately 200 acres of the parish of Cullen Bullen in the County of Roxburgh. At Kirby's Hill itself a maximum of about 300 feet of Coal Measure rocks rests on Upper Marine beds, and this is one of the most westerly exposures of the Upper Coal measures. The purpose of scout drilling was to determine the suitability of the Lithgow and Irondale Seams for open cut exploitation.

Two methods are outlined in this report. The first, is a method intended for the determination of porosity of consolidated sediments. The method is applicable to those sediments included in rotary drill cores and hand specimens of rock collected in the field. The second, is a method intended for the determination of permeability. It is applicable to suitably sized samples of rocks and any other substances whose constitutions permit of their being treated by the procedure set out in this method, subject to their own inherent limitations relative to this method. This report provides a detailed description of each of these methods.

During an inspection of limestone deposits at White Rocks on 2/11/50, samples of weathered granite were collected from a quarry on the eastern side of the Queanbeyan-Cooma road, about 150 yards south of the two-mile peg. This quarry is in the Queanbeyan Clay Deposit described by W.G. Woolnough in departmental reports dated 17/2/28 and 20/6/28. If the rock can be economically crushed and worked, it may be suitable for the production of sewer-pipes and other impervious ware. The samples, reserves, and suitable uses for the granite are described in this report.

The boring campaign carried out during 1950 by the Petroleum Technology section of the Bureau proved the existence over an area of 25 square miles in the Oaklands-Coorabin coalfield of approximately 793,000,000 tons of coal with an average calorific value of 9150 B.Th.U. per 1b. Thickness of the coal intersected in the bores ranged from 18 to 59 feet and depth to the coal from 186 to 565 feet. This report comprises detailed coal analyses, notes on the geological results, and recommendations for future boring.

Attention has been directed to the cobalt workings at Carcoar as a possible source of radioactive minerals in two ways. During testing of museum specimens for radioactivity, it was found that cobalt ore from Carcoar was strongly radioactive. Also, the occurrence of uranium in the cobalt ores was reported by Mr. McKillop, formerly a land holder in the area, who submitted a copy of a report signed by Professor T.H. Laby, certifying the presence of uranium in samples examined by him, and at a later date, a sample containing an uranium mineral. A brief visit was paid to the area in 1948, and the presence of strong radioactivity on dumps was confirmed. A more extensive survey of the area was, therefore, undertaken by geophysicists during 1949-50 and 1950-51. This report gives an account of the geophysical operations carried out in the vicinity of the Carcoar cobalt workings and describes the results of these investigations.

The beach sands on which investigations were carried out, were mainly from beaches along the eastern coast of Australia and from islands adjacent to this coast. A high percentage of the mineral grains of the heavy mineral fraction in these sands have grain sizes within the range -100 to +200, referred to British Standard Sieves. The grain size of the minerals, combined with the fact that the grains are quite well rounded, makes the heavy mineral sands an ideal subject for separation using the inclined method with the Isodynamic Separator. The use of this method, and the results obtained, are described in this report.

A reconnaissance geological and radiometric survey of the Mt. Cavenagh area was carried out by B.P. Walpole and J. Sleis of the geological section and J. Daly and D. Dyson of the geophysical section of the Bureau of Mineral Resources. The objects of the survey were to examine reported occurrences of radioactive minerals in this area and to determine whether further prospecting of the area for radioactive orebodies was warranted. The general geology of the area, and the economic geology of the six prospects examined, are described in this report.

The Crater Line consists of a series of rock exposures outcropping in an arcuate pattern around the southwestern flank of the Rum Jungle granite. The exposed rocks are believed to represent part of the Brocks Creek group of Lower Proterozoic age. The Crater formation, the major mappable unit in the line of exposures, consists of metamorphosed clastic rocks totalling approximately 1500 feet in thickness. Significant radioactivity is restricted to three stratigraphic zones within the Crater formation. These have been mapped and are designate Crater Pebble Beds, Number One Pebble Bed, and Number Two Pebble Bed. Number One Pebble Bed appears to contain the most significant anomalies. The radioactivity is restricted to conglomerate beds. There may be a genetic relationship to the greater permeability formerly localized in the conglomeratic zones. The radioactivity is not localized by tectonic structures such as folds, faults, or changes in dip. No source of the radioactivity has been identified. The radioactivity probably emanates from members of the uranium disintegration series. Four areas containing significant anomalies and deserving further investigation were found along the Crater Line.