Increases in atmospheric CO¬2 cause the oceanic surface water to continuously acidify, which has multiple and profound impacts on coastal and continental shelf environments. Here we present the carbonate mineral composition in surface sediments from a range of continental shelf seabed environments and their current and predicted stability under ocean acidifying conditions. Samples come from the following four tropical Australian regions. 1. Capricorn Reef (southern end of the Great Barrier Reef). 2. The Great Barrier Reef Lagoon. 3. Torres Strait. 4. The eastern Joseph Bonaparte Gulf. Outside of the near-shore zone, these regions typically have a carbonate content in surface sediments of 80 wt% or more. The abundance of high magnesium-calcites (HMC) dominates over aragonite (Arag) and low magnesium-calcite (LMC) and makes up between 36 and 50% of all carbonate. HMC is significantly more soluble than Arag and LMC and the solubility of HMC positively correlates with its magnesium concentration. Using the solubility data by Plummer and Mackenzie (1974) (1), 96% of HMC in the four regions is presently in thermodynamic equilibrium or slightly supersaturated relative to global mean tropical sea surface water. When the modelled saturation state for aragonite in equatorial areas for this century (2) is converted into HMC saturation state curves, HMC is predicted to become undersaturated in the four regions between 2040 to 2080 AD with typical HMC decline rates between 2 and 5% per year. The range of respective estimated carbonate dissolution rates is expected to exceed current continental shelf carbonate accumulation rates leading to net dissolution of carbonate during the period of HMC decline. In a geological context, the decline in HMC is a global event in tropical continental shelf environments triggered by reaching below-equilibrium conditions. The characteristic change in carbonate mineral composition in continental shelf sediments will serve as a geological marker for the proposed Anthropocene Epoch.

The Bulong vermiculite deposit, situated 20 miles east of Kalgoorlie was discussed with members of the West Australian Mines Inspection Branch. The geology, quality, and production potential of the deposit are discussed in this report.

The presence of laterite described as high-silica bauxite at Mt. Roe on Cobourg Peninsula had been reported early in this century by H.Y.L. Brown, who submitted a specimen for analysis. In the absence of information about the mineralogical composition of the rock the chemical analysis alone affords a very incomplete description of the material. It was considered that the rock might be somewhat similar to the commercially valuable high-silica bauxite which occurs in the Netherlands East Indies and Malaya. At the request of the Australian Aluminium Production Commission the writer was instructed to examine the area in the vicinity of Mounts Roe and Bedwell, and to sample and report on any accessible bodies of apparently aluminous laterite. The locality, topography, and general geology of the area are briefly described. Accounts of the laterite occurrence at Mounts Roe, Bedwell, Kura, and Victoria are given. The mineralogical character of the laterite is described.

In the Northern Territory laterites are formed in situ as: (i) an illuvial soil horizon; and (ii) a chemical lake laterite deposit. The end product of extensive weathering processes of certain favourable beds is considered by some to be a true mature laterite, whereas others believe it is merely a duricrust. The denudation of laterite and transportation, deposition and cementation of the fragments with other rock fragments result in a detrital laterite deposit. Water-rounded rock fragments in the detrital laterites are readily coated and cemented with iron oxides and resemble the pisolites in the ferruginous zone of the lateritic profile. This similarity results in an exaggeration of the true extent of laterization. The similarity in environmental conditions between the process of precipitation of uranium minerals and laterization is discussed. True mature and detrital laterites are illustrated by photographs.

The mineral resources sector plays a vital role in Australia’s ongoing economic prosperity. The sector dominates the nation’s export earnings, provides substantial direct and indirect employment and investment in regional and indigenous communities, supports downstream and service industries, and delivers essential revenue to governments.

The collection supports the compilation of national mineral resource and production statistics, and mineral prospectivity analysis. The collection includes the OZMIN database (Australian mineral deposit descriptions including geological, resource and production data); the MINLOC database (mineral occurrence locations sourced from Geoscience Australia and state and territory geological surveys); supporting GIS datasets (eg,mineral prospectivity datasets, ports, power stations); maps and reports.

Two samples of diatomite were recently received from Broken Hill Pty. Co. Limited for microscopic examination. They were from Nettle Creek, 9 miles north-east of Mt. Garnet and near Innot Hot Springs. The results of the microscopic examination are given in this report.

This report is written primarily to present the determination of the permeability and porosity of a number of rocks and minerals, but it has also been considered advisable to give a brief description of the different kinds of apparatus designed and used in making the determinations. The materials on which the tests were carried out included a suite of specimens from No. 10 bore, Lakes Entrance, two specimens of sandstone from one of the bores at Roma, Queensland, and a number of Australian diatomites. The method of presentation adopted in this report is, firstly to describe the apparatuses used in making the determinations and the technique adopted in preparing the specimens for testing and secondly to discuss the results obtained for each set of specimens. In addition to the permeability and porosity tests already mentioned, a number of tests of compressive strength were made on wet and dry samples of glauconitic sandstone from Lakes Entrance.

These notes are compiled as a result of conversations with Government officials and mining engineers in Noumea on 4-6th July, 1951. Figures are given for the production, reserves, and exports of Nickel, Chromite, Manganese, Cobalt, Iron, and other miscellaneous minerals. Most of the figures quoted herein have been compiled from records collected by the Australian Consul.

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.