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BRIEF HISTORY OF MINING

Alunite was mined from 1878 to 1927, then again from 1934 to 1950, output about 72,165 tons.

The maximum annual production was 3,644 tons in the year 1902. The mine closed down in 1952.

In mid 1952, Alunite (Aust.) Pty. Ltd., the only producer ceased supplying the parent company, Sulphates Ltd., because of rising freight charges to Victoria. There has been no production in recent years.

The natural phenomenon that is the Alum Mountain is the only known alunite deposit of potassium bearing minerals in N. S. W. The mountain is a mass of altered rock, possibly Trachytic or Rayolitic with associated sediments, some 900 feet high and 3 miles long. It was first mined in 1878 when the Run Corn Alunite Company was formed.

The Run Corn Alunite Company mined from the centre of the rock face until 1883-84. All treatment was carried out at the mine, a railway line was built from the mine to the wharf where the treated alunite was taken by water to Windy Woppa, where it was used as ballast in boats returning to England.

A new mining company was formed in 1888, and formed 'The Big Quarry' on the other side of the small mountain; this was worked until 1910 then being sold to the 'Australian Alunite Company' with its head office in Melbourne.

VALUE OF ALUNITE RECOVERED

Since 1890, the quantity of alunite recovered and treated from the Bullahdelah Mountain exceeded 60,489 ton, the value of which was £190,103.

GEOLOGISTS' REPORTS

Mr. L. F. Harper Sen. - for Geological Surveyor, of the Department of Mines, has furnished a report on the deposit. This states that the only workable deposit of alunite yet found in New South Wales is close to the village of Bullahdelah, on the Myall River, which flows into Port Stephens. The village is about 60 miles north of Newcastle, from which a triweekly motor service runs. Attention was directed to this deposit in 1888, the first lease being taken up in November of that year by the Australian Alum Company. Since then the company has acquired a much larger area, and worked the deposit more or less continuously to the present time.

Mr. E. F. Pittman, a former Government Geologist of New South Wales, has described the occurrence, and the following is an optima of his views: -

'The township of Bullahdelah is built on beds belonging to the Upper Marine Series of the Pero-Carboniferous System. About three quarters of a mile east of the village a narrow mountain range occurs, with maximum height of 900 feet, composed almost entirely of the mineral alunite of greater or less purity.'

The central escarpment in Mr. Pittman's opinion is apparently formed of a steep anticline. The presence of rhyolites is recorded, also masses of dykes of volcanic glass (obsidian), and the opinion expressed that the rhyolities are interbedded with the permocarboniferous rocks, and were outpoured as contemporaneous lava sheets. In gaps in the range the presence of dykes of dolerite was noted. The bulk of the material forming the range is recorded as being too impure for commercial purposes, but there was evidence of the occurrence of large deposits of high grade mineral.

As regards to the origin of the deposit, Mr. Pittman expressed the opinion that the alteration of the rhyolites by steam and sulphurous acid vapours following the intrusions of delerite during the Teriary period was responsible. Analysis of four varieties of alunite are given. In 1917, the Australian Advisory Council of Science and Industry issued a bulletin, which included the Bullahdelah deposit. The mistake commonly made of referring to the occurrence as a mountain of alunite is mentioned in the publication, and it is stated therein that: -

'....the higher grade mineral occurs only in patches or enrichments of the main body of low grade material.'

Numerous analyses and laboratory tests are included in this publication. During the latter part of 1923, I examined the occurrence. This examination was made with a view to supplying information as to future prospecting for deposits of commercial alunite. The examination was of reconnaissance nature only, but my observation led me to consider that the Bullahdelah mountain in all probability represented a faulted rock mass, and that the origin of the alunite was due to the circulation of steam and sulphurous acid vapours along the fault places and subsidiary cracks.