Manganese deposits in the Gregory Range, Western Australia were examined and mapped by officers of the Geological Survey of Western Australia and the Bureau of Mineral Resources jointly. The investigation indicated the presence of 93,000 tons of manganese ore distributed between 37 separate bodies contained in 13 groups. Numerous small bodies each containing less than 200 tons of ore have not been included in the tonnage estimate. The grade determined by chip sampling the surfaces of the outcrops is generally high. The range of composition of samples is: [see table in record]. The deposits occur as replacements of silicified bands in dolomitic limestone and as fillings of irregular cavities in the limestone. A few thin deposits in the south-eastern sector of the field overlie quartzose rocks.

The McMillan deposit is in the southern portion of the Logan Mountains, 65 km NE of Watson Lake. It is also referred to as the Quartz Lake deposit. Rocks hosting the deposit consist of argillite, sandstone, limestone and massive sulphides. Mineralization includes concordant and discordant types. Concordant mineralization mainly consists of beds of massive sulphides with sphalerite, galena and carbonate (siderite?) with minor sulphosalts. Discordant mineralization is widespread and consists of veins and veinlets that cut layering and cleavage. Quartz-siderite is the most common vein filling. Most stratabound deposits in Selwyn Basin are attributed to syngenetic origins. However, deposits similar in mineralogy and geologic setting to the McMillan deposit are thought to be of a replacement type origin. Two models are proposed for the origin of the McMillan deposit:: a) mineralization was hydrothermally introduced into a carbonate-rich post depositional sequence and selected limestone beds were replaced by sulphides and siderite, or b) the mineralization was hydrothermally introduced onto a seafloor and sulphides and siderite were precipitated as lateral facies equivalents of limestone.

Superficial deposits of ferruginous manganese ore occur on the southern end of the Teano Range, Peak Hill Goldfield, Western Australia at about 150 miles by road north-north-west from Meekatharra. During the course of an investigation of new manganese discoveries in north-west Western Australia by L.E. de la Hunty of the Geological Survey of W.A. and the writer, the opportunity was taken to inspect two groups of small deposits in the Teano Range. One group contains about 14,200 tons of ore which averages about 2 per cent manganese and 32 per cent iron, and the other group 4,000 tons of marginal grade containing about 46 per cent manganese and 3.5 per cent iron. The former group is not of marketable quality and the other is too small and too remote to be of commercial value.

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The maps show Australian manganese resources by regions and deposit types

The maps show Australian manganese resources by regions and deposit types

The maps show Australian manganese resources by regions and deposit types

The maps show Australian manganese resources by regions and deposit types