The opal industry in Australia has experienced a marked revival during the past few years, and the value of production during 1946 was the highest recorded for 40 years. To some extent this is due to the purchases made by American troops when they were stationed in this country during the war, and the publicity given to the gems when the troops returned to their homes. Apart from the direct effect of this publicity on the demand for tl1e gem, the discovery of good stone in a hitherto unprospected portion of the principal field led to considerable improvement in production. It is frequently pointed out that Australia is the principal opal-producing country in the world, and that this pre-eminence should enable us to exercise what amounts to international control of the industry. Whilst there are cogent arguments against any attempt to establish world control, a good case may be made for a greater degree of economic stability in the industry within Australia. The possibility of devising a method which would be in the best interest of all sections of the industry was investigated by the Bureau of Mineral Resources, and the results of the inquiry form the subject of this Bulletin. It is appropriate to emphasize several points which must be kept in mind if the opal industry is to be considered in its proper perspective. As far as can be ascertained there is no commercial use for opal other than as a gemstone, and it must, therefore, be regarded as a non-essential luxury item. Although opal may have a considerable value as an export commodity, the industry is subject to vagaries of fashion and other unpredictable factors which make stabilization extremely difficult. Besides this disability is the relative insignificance of opal production compared with that of other minerals on the basis of recorded value it constitutes less than 005 per cent of the total 8 mineral production in Australia. It should be clearly understood, therefore that a small non-essential industry is under review, and any departure from this perspective will lead to misunderstanding of the views expressed in this Bulletin. For these and other reasons it will be understood that values of production quoted in this Bulletin must be regarded as comparative rather than absolute, and it may be safely assumed that they are all under-estimated. The remainder of this Bulletin is divided into two major parts-the first dealing with the raw material, and the second dealing with the marketing aspects and a discussion of the various methods which have been suggested for stabilization of the industry. Emphasis throughout is on the present rather than the past, although some historical data are included as essential to a proper appreciation of the present circumstances in the industry.

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Consequent upon instructions received from the Superintending Geologist, Mr. C.J. Sullivan, the copper-gold deposit at Yeuralba was visited and inspected on the 9th, 10th, and 11th May, 1950. This geological report gives an overview of the inspection and its findings. The situation, history, workings, general geology, orebody, mineralisation, and production history of the deposit are briefly described.

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.

Following a report by Mr. McDougall of the existence of sulphur deposits, possibly of large dimensions, on New Britain, deposits at Lolobau, Pangalu and Kasolali were examined in the early part of June, 1950, by the Chief Geologist, accompanied by A.K.M. Edwards, Senior Geologist, Port Moresby and G.A. Taylor, Vulcanologist, Rabaul. This report gives an account of the examination and its findings.

The deposits of heavy mineral sands along the East Coast of Australia are being investigated primarily to determine their content of monazite. These deposits contain most of the known world reserves of zircon and rutile for which they are being exploited at various localities. Monazite, a phosphate of cerium, lanthanum, praseodymium and other rare earths, with thorium silicate, is utilised commercially as a source of cerium and of thorium. In this investigation, the thorium content on the monazite is being determined on the basis of its radioactivity. A principal deposit, and two smaller deposits, in the Fingal-Cudgen area were investigated. The geology of the area, methods of testing, and the results of the investigation are discussed in this report.

This report has been written as the result of conversations between the writers and officers of the Joint Coal Board in Sydney, Lithgow and Cessnock, and with similar assistance from the Geological Survey of New South Wales. The writers visited the Western and Northern coalfields during August and inspected most of the operating open-cuts. The results of the enquiries are presented in five tables which are set out at the end of this report and which contain, in statistical form, the greater part of all the information elicited. The text matter of the report is explanatory of the tables and also discusses the methods which have been used in arriving at the estimates of coal reserves. In the ensuing discussion emphasis has been laid on coal reserves available for open-cut mining, and all enquiries directed to the Join Coal Board were concerned with open-cut coal only.

For the first time the hypostoma of an eodiscid trilobite, Pagetia bootes Walcott, is described. The presence of a doublure with terraced lines, and schizochroal eyes as observed on Australian Pagetiae, is mentioned. Obviously the trilobite nature of the Eodiscidae is no longer in question.

This collection of fossils from the Portland area consists chiefly from mollusca, but where a small portion of sediment was attached to the fossils, it was removed and washed down for micro-examination. The number given to each sample refers to the registered number in the Victorian Geological Survey Collection. The results of the examination are recorded in this report.