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.

This report presents the results of a geological investigation of the Crusader copper deposit, Dobbyn, Queensland. The purpose of the survey was to investigate the geological setting of the Crusader Mine and thereby to determine the factors controlling the deposition of ore, and the possibility of producing ore from the deposit. An area of about six square miles was mapped using enlarged aerial photographs, and a plane table survey was made of the miner area, using a telescopic alidade.

The Cobar mining field was examined between August, 1946 and June, 1947. Attention was concentrated on the operating mines, viz. New Occidental, New Cobar and Chesney. New Occidental Gold Mines, N.L. owns all three deposits and had requested assistance from the Commonwealth Government to search for new orebodies on their leases. It had previously been recognised that each of these orebodies lay close to a sharp contact between fine-grained and coarse-grained sediments. Of particular interest are the portions of the contact which have been subjected to minor folding, because, immediately to the south of these folds, fracturing favourable for ore localisation has developed. The geological examination was carried out in conjunction with the Geological Survey, Mines Department, New South Wales. Surface and detailed underground mapping were carried out. A preliminary magnetic survey of part of the field was carried out by the Geophysical Section during the first half of 1947. A special study of the New Cobar Mine and the plans of that deposit were made by Dallwitz, Fleischman and Ivanac. This report provides a comprehensive overview of the situation, topography, history, structural geology and general geology of the area. Detailed descriptions are given of the history, workings, orebodies, and structure of each individual deposit. Various accompanying plans of the mines and the Cobar mineral field are included.

The mine manager at Mount Bischoff Tin Mine, Mr. Eddy, proposes to mine the Greisen Orebody by means of a system of gloryholes, in combination with stoping. It was requested that a scheme of development work necessary for opening up the orebodies preparatory to mining should be decided on and set out on paper. This report is concerned with the proposals for development and testing work which would determine whether the larger gloryhole would be justified or whether a smaller gloryhole on the hanging wall ore and stoping on footwall ore would be a more profitable method.

The geology, production history, ore grade, and ore reserves of the Northern Star Mine are discussed in this report. Four accompanying plans are included.

The Mont Murphy reefs occur in sedimentary rocks, which strike northwest and dip southwest at 45 degrees, about 31/44 mile north from an intrusive granite contact. The reefs, which strike north to northeast and dip steeply east, can be divided into three groups - the No. 1 reef, the No. 2 reef, and the Upper Mount Murphy group. Total positive plus probable ore on present mine exposures adds up to 1,132 tons, containing 18 tons tungstic oxide worth £9,900. Possible additional ore is about 2,500 tons with a tungstic oxide content of perhaps 41 tons. There is little prospect of capital invested being returned but the mine may pay operating costs if working expenses are kept to a minimum.

It has been fairly firmly established that the fineness of the gold in any ore deposit varies with the depth from the surface at which the deposit was formed and as a corollary to this, that it is dependent upon the temperature and pressure at the time of deposition. This relationship is such that, under certain conditions, the gold fineness, taken into consideration with other recognised criteria, furnishes a very sensitive and reliable guide to the relative temperature of ore formation, at least within the epithermal and the upper part of the mesothermal range. The definition, determination, relation to deposits, and application of gold fineness are discussed in this report.

The Great Cobar ore deposit was discovered in 1870. Production commenced in 1871 and since that date mining at Cobar has been more or less continuous. The field has produced copper, gold, and silver to the value of approximately £A27,000,000. Cobar has been the most important producer of copper in New South Wales, and in recent years, has also been the most important gold-mining centre. The Zinc Corporation Limited is carrying out, with the aid of the Bureau, an extensive geological and geophysical examination of the area, with the hope of finding other orebodies. The Bureau itself has extended geological mapping over an area of approximately 2,000 square miles in the Cobar-Nymagee-Canbelego district with the ultimate aim of discovering other ore deposits, or even fields of the Cobar type. In the Nymagee district, North Broken Hill Limited is also carrying out, in co-operation with the Bureau, an extensive exploration programme. The history, production, reserves and prospects of the New Occidental, Chesney, and New Cobar mines are discussed in this report.

The present report gives an overview of the general geology and ore geology of the Blue Spec Mine. The main orebodies are described in some detail. General estimates of reserves and recommendations for future geological work are noted.

The object of this tour was to study ore deposits and methods of exploration in Africa and North America as well as to attend, as Official Delegate of the Commonwealth of Australia, the 19th International Geological Congress held at Algiers in September, 1952. A considerable amount of information was gained concerning ore deposits in the countries visited and this information should be of assistance in the search for further metal deposits in Australia. At the international Congress useful work was achieved and contact was made with a large number of geologists in various parts of the world. These contacts will facilitate the exchange of information between Australia and foreign geologists. The itinerary followed the attached as an Appendix to this report.