This geophysical survey was undertaken as part of a campaign by the N.S.W. Mines Department and the Commonwealth Bureau of Mineral Resources to explore the ore possibilities of the Cobar Mining Field. Tests, made in January 1947, on specimens of ore from the operating mines showed that some of the ore from the New Cobar and Chesney Mines exhibited appreciable magnetisation due to its pyrrhotite and possibly magnetite content. The survey was commenced in March, 1947 using the magnetic method only as a first method of attack. Watts Vertical Force Variometers Nos. 15887 and 16128 were used, the field work being carried out by the writers. The geology of the area, object of the survey, results, and recommendations for future drilling are discussed in this report. Two accompanying plans are included.

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.

When the question of iron ore resources in Australia was being considered in 1937 and 1938, it was stated in departmental reports that information concerning the deposits and reserves of iron ore was incomplete, but that sufficient was available to indicate that Australia possessed very small reserves of iron ore in comparison with those of other continents and that the actual reserves were small and sufficient to last for only 50 to 100 years dependent on the future rate of consumption. This report summarises the current position regarding the resources of iron ore deposits throughout Australia. Two tables are appended detailing the production and export of iron ore for 1926-1944, and iron ore used, 1937-1944.

At the request of Mr. G. Lindesay Clark, Deputy Controller of Minerals Production, estimates have been made of the grade of ore likely to be delivered to the mill during the next two years under conditions of half-scale production. The methods of estimating tonnage and grade, as well as the resultant estimates, are discussed in this report.

A diverse range of mineralisation, including porphyry and epithermal deposits, intrusion-related gold and other metal deposits, iron oxide-copper-gold (IOCG) deposits and orogenic gold deposits all have linkages to crustal growth and magmatic arcs. Furthermore, all of these deposit types are associated with fluids containing H2O, CO2 and NaCl in varying and differing proportions. In all cases, it can be argued that magmas are a key source of hydrothermal fluids for these types of mineral system, and that subduction processes are critical to controlling fluid chemistries, the metal-bearing capabilities of the fluids and depositional processes. The differences on typical/bulk fluid chemistries between deposit types can be explained in part by differences in the P-T conditions of fluid segregation from its magmatic source. The most significant control here is the pressure at which fluid forms from the magma as this has a strong effect on fluid CO2/H2O values. This is clearly exemplified by the rare occurrence of readily detectable CO2 in deep porphyry systems (Rusk et al., 2004). On the other hand, fluid Cl contents (which strongly influence its base metal carrying capacity) are very sensitive to the magma's bulk composition. However, only some subduction-related magmas are fertile, and the differences do not seem to be due solely to variations in effectiveness of depositional processes. So what controls the volatile content of the magmas? Isotopic and other evidence, in particular for S and Cl, shows (unsurprisingly) that the greater contents of these elements in arc magmas compared to other melts is due to contributions from subducted materials, although there may be additional, lower crustal sources of Cl. Variations in the budget of volatiles subducted may thus play a role in controlling the chemistry of magmas and associated hydrothermal fluids, but variations within individual arcs suggests that again this is not the entire story.

This database contains geochemical analyses of over 7000 samples collected from or near mineral deposits from 60 countries, compiled by the Critical Minerals Mapping Initiative (CMMI), a collaboration between Geoscience Australia (GA), the Geological Survey of Canada (GSC) and the United States Geological Survey (USGS). Data was compiled from a number of publicly-available sources, including federal and provincial government mineral deposit and geochemistry databases, and the ore samples normalised to average crustal abundance (OSNACA) database compiled by the Centre for Exploration Targeting at the University of Western Australia. Geochemical data cover the majority of the periodic table, with metadata on analytical methods and detection limits. Where available, sample descriptions include lithology, mineralogy, and host stratigraphic units. Mineral deposits are classified according to the CMMI mineral deposit classification scheme (Hofstra et al., 2021). Location information includes deposit or prospect name, and sampling location (i.e., mine, field site, or borehole collar). This dataset will be updated periodically as more data become available. Geoscience Australia: D Champion, O Raymond, D Huston, M Sexton, E Bastrakov, S van der Wielen, G Butcher, S Hawkins, J Lane, K Czarnota, I Schroder, S McAlpine, A Britt Geological Survey of Canada: K Lauzière, C Lawley, M Gadd, J-L Pilote, A Haji Egeh, F Létourneau United States Geological Survey: M Granitto, A Hofstra, D Kreiner, P Emsbo, K Kelley, B Wang, G Case, G Graham Geological Survey of Queensland: V Lisitsin

The Wilks Creek wolfram mine is situated in the parish of Steavenson, county of Anglesey in central Victoria. It is approximately 4 miles south from the small town of Marysville, a popular tourist resort, and 61 miles by road northeast from Melbourne. Underground and surface mapping was carried out on the 23rd and 24th November, 1943, with compass, tape and Abney level. This report comprises an overview of production history, general geology, economic geology and ore reserves.

"Greisen Lode" is the name given locally to the foot-wall section of a wider mineralised zone, which will be referred to as the Greisen Orebody in this report. Mining operations have been carried out by tributers in recent years on several portions of the orebody, namely, stoping from the Main Tunnel, stoping from an adit-crosscut driven from the No. 4 Gossan Bench, and some stoping operations from a level above the latter bench. During the past three months a level has been driven for 260 feet westwards from the Main Tunnel to prospect the orebody at this level and develop it for mining. Over the past few weeks a detailed geological examination of the orebody has been made and the area involved mapped on a scale of 20 feet to an inch by means of plane table and 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 Blue Spec Mine, Nullagine, was visited from 20th to 24th September, 1947. An inspection was made of the mine. No. 3 level (depth 450 feet) was mapped and the antimony-gold occurrences on lease 196, and on the property known as "Blacks", were also briefly inspected. The present position regarding water supply was investigated and recommendations made. The ore reserves, workings, economic considerations, and water supply are discussed in this report.