AUSTRALASIA
Australia
The most important occurrences of platinum in the Commonwealth are at Fifield and at Platina, in New South Wales.
The outputs of crude platinum in Australia in recent years were all exported to the United Kingdom as under:
| Year. | Troy oz. |
|---|---|
| 1910 | 332 |
| 1911 | 470 |
| 1912 | 610 |
| 1913 | 442 |
| 1914 | 244 |
| 1915 | 56 |
| 1916 | 82 |
| 1917 | 259 |
| 1918 | 607 |
Note.—These figures do not include the osmiridium produced in Tasmania.
Recent imports of manufactured platinum were as under:
| Oz. | |
|---|---|
| 1910 | 320 |
| 1911 | 504 |
| 1912 | 318 |
| 1913 | 301 |
| 1914–15 | 223 |
| 1915–16 | 89 |
| 1917–18 | 18 |
The question of the refining of platinum in Australia has been under consideration for some time; so far the crude material has all been sent to England. The outlook for future production of crude platinum in Australia is not promising, with the exception of that of Bald Hill district, Tasmania.
New South Wales.—Platinum is obtained at Platina, in the Fifield division, in the east central part of the State, from a buried gravel channel, in which it occurs in association with gold and osmiridium. The rocks in the vicinity of the “leads” consist chiefly of slates, but the source of the platinum is not known[[4]] p. 557. These deposits were first exploited in 1894, and from that year to 1918 inclusive, the total output of platinum from New South Wales was 14,680 oz.[[40]]. The gravels have yielded amounts of 6 dwt. platinum and 2 dwt. gold per ton, but according to Government reports the richer deposits are nearly worked out; mining operations are carried on with great difficulty, as there is a great scarcity of water and a deep overburden, varying from 20 to 80 ft. in depth. It is estimated that there are 200 acres of platinum-country available, sufficiently rich to pay, were it worked on a large scale with an abundant supply of water[[41]].
A new occurrence has recently been discovered about 1 mile distant from the old Platina deep “lead,” the platinum being associated with small quantities of gold. The “lead” has so far been proved to extend over an area about 1 mile in length, and from 60 to 150 ft. in width, the wash varying in depth from a few feet to up to about 80 ft. The pay gravels, which rest on shales and sandstones of Silurian and Devonian age, intruded by dioritic dykes, are stated to be from 1 to 3 ft. thick. The following analysis is representative of the crude platinum produced:
| Per cent. | |
|---|---|
| Platinum | 75·90 |
| Iridium | 1·30 |
| Rhodium | 1·30 |
| Palladium | trace |
| Osmiridium | 9·30 |
| Iron | 10·15 |
| Silica | 1·12 |
| [[42]] p. 14. | |
Platinum is frequently found in beach sand deposits on the coastal border between Queensland and New South Wales, notably at Ballina, close to the mouth of the Richmond River; at Evans Head, further south; and at Currumbin, near the mouth of the Tweed River. In this locality black sands containing platinum, associated with gold, cassiterite, monazite and osmiridium, accumulate on the beaches during stormy weather. At Ballina and Evans Head, the platinum predominates over the gold, but at Currumbin, further south, the gold is in the greater quantity[[4]] p. 557. The minerals are present in a very finely-divided state, and separation of the valuable metals is a matter of considerable difficulty. The problem does not appear to have been satisfactorily solved up to the present time, although promising experiments have recently been carried out with screening and magnetic treatment. The deposits are, unfortunately, very low grade.
The sources of the metals are uncertain. The platinum and osmiridium appear to have been derived from the western edge of the Clarence coal measures, which now exist only as fragmentary outcrops. The gold, tin and monazite may have their origin in granite and other rocks of the New England tableland. Chromite is present in some of the Currumbin sands, which suggests serpentine as the probable source of platinum[[4]] p. 557. Other associations are zircon, garnet, tourmaline, ilmenite, magnetite and sapphire.
In the Broken Hill district, principally at Little Darling and Mulga Springs Creek, platinum has been proved to extend over a considerable area in a copper-nickel gossan, closely associated with gabbro, decomposed gneisses and schists. In addition to platinum, the amounts of which vary from a trace to 16 dwt. per ton, gold, silver, iridium and palladium are also present[[43]]. The deposits bear some resemblance to the nickel deposits of Sudbury, Ontario, and it is thought that here, too, the platinum occurs combined with arsenic, as sperrylite.
Queensland.—In addition to the beach deposits between Southport and Currumbin, described above, platinum has been found in Coopooroo and Wairamba Creeks on the Russell Goldfield, near Innisfail; also in the Lucknow and Alma “reefs” of the Gympie Goldfield, where it is present in quartz lodes with native gold, and arsenopyrite, the accompanying rocks consisting of slates, alternating with volcanic tuffs and conglomerates; the metal also exists in the neighbouring gold-bearing alluvial deposits of Brickfield Gully.
Another occurrence of alluvial platinum is known at the head of the Don River in Central Queensland[[4]] p. 556.
Victoria.—Platinum occurs in the Walhalla Copper Mine, where it is associated in a hornblende-diorite lode-formation with copper pyrites, gold and silver. The ore is stated to contain from 2 to 7 dwt. platinum per ton. In the Thompson River Copper Mine platinum is found in a hornblendic rock rich in chalcopyrite.
Tasmania.—Iridosmine has been produced from the Bald Hill district near Waratah, in the north-western part of the state, since 1900, the metal being obtained from placer deposits in Nineteen Mile Creek and its tributaries, Linger-and-Die, McGinty’s and Barren Creeks, and from Savage River. It has been located in situ in the rocks of Bald Hill, principally in serpentine, but also with chalcedony and opaline silica in lode-formations. In the former case, it is associated with magnetite, pyrite, pyrrhotite, nickel and gold. The iridosmine in the placer deposits is sometimes coated with iron oxide, and is also at times found enclosed in chromite. The following analysis in percentages, made at the Imperial Institute, is typical: osmium, 57·09; iridium, 33·80; platinum, 0·37; ruthenium, 8·19; palladium, 0·21; gold, 0·04; iron, 0·30; copper, trace.
Other localities in Tasmania at which osmiridium has been located are Heazlewood River, Whyte River, Castray River, Huskisson River, Wilson River and Boyes River; also the Badger gold diggings, west of Savage River, and the Salisbury goldfield near Beaconsfield.
The following table gives the recent annual output of osmiridium in Tasmania:
| Year. | oz. (troy). | Value in £. |
|---|---|---|
| 1910 | 120 | 530 |
| 1911 | 272·9 | 1,188 |
| 1912 | 778·8 | 5,742 |
| 1913 | 1,261·6 | 12,016 |
| 1914 | 1,018·8 | 10,076 |
| 1915 | 247 | 1,581 |
| 1916 | 222·2 | 1,899 |
| 1917 | 332·1 | 4,898 |
| 1918 | 1,607 | |
| 1919 | 1,669·7 | 39,614 |
South Australia.—In the north-east part of the State traces of platinum have been recognized by analysis as occurring in the outcrop of a lode near Boolcoomatta. Further information on this occurrence is not available.
Papua.—Osmiridium, associated with small amounts of gold only, is known to occur as alluvial in the neighbourhoods of various serpentine areas; in the Lakekamu district, in flaky form; in the Yodda Valley, in appearance similar to native bismuth; and in other places in shot-like granules[[44]].
New Zealand
Platinum is only obtained commercially in New Zealand from the Orepuki district of Southland, where it is produced by the Round Hill Gold Mining Company as a by-product in the washing of auriferous gravels. According to information recently supplied by the Mines Department, the annual output of crude platinum for the last ten years has averaged 30 oz., but in view of the recent falling-off of the gold production in this locality, the prospects of any increase in the output of platinum seem small.
In South Island the presence of platinum has been reported on the Thames River in quartz lodes, in a region of serpentine and diorite, and in a pyritic lode near the Taramakau River in the district of Westland, in close proximity to sheets of altered magnesian eruptive rocks[[4]] p. 557. The platinum in the latter case occurs in association with silver, in the proportions of about 7 parts of the latter to 1 of the former, together with pyrite and limonite. Samples taken from the lode have been stated to have an average content of 3 dwt. 8 gr. platinum per ton[[45]].
Other localities in South Island where platinum has been located are the Taraka and George Rivers, which flow into Awarua Bay; the east coast of Otago, in beach sands and river gravels; the Clutha River; and the Nelson gold district.
Concentrates containing up to 2·5 per oz. per ton are reported to have been obtained from the Parapara sub-division. Platinum in New Zealand is often associated with gold, and the deposits are in many cases similar to those of the Urals.