SOURCES OF SUPPLY OF PLATINUM AND ALLIED METALS
(_a_) BRITISH EMPIRE
The outputs of platinum metals in different parts of the British Empire
are shown in the table on p. 14.
EUROPE
UNITED KINGDOM
There is no known occurrence of platinum in the United Kingdom, but
there has always been much trade done there in the platinum metals,
England having been the second largest importer of the big consuming
nations. The following were the importations of Russian platinum for
five periods since 1863:
_Period_ _Oz._
1863–1880 512,005
1881–1890 167,999
1891–1900 437,645
1901–1910 259,111
1911–1915 71,624
[15] p. 923
The above figures do not include receipts of platinum for seven
different years since 1863, for which there are no records.
The table on the next page gives a summary of total imports of platinum
metals for the years 1910–1918, with the countries of origin.
The platinum market in London was controlled by the Government from
January 1916 to December 1918, Johnson, Matthey & Co., Ltd., acting as
buyers. On December 26, 1916, platinum was declared contraband.
_Imports of Platinum Metals, wrought and unwrought, into United Kingdom_
(_in troy oz._)
───────────────────────────┬──────┬──────┬──────┬──────
│1910. │1911. │1912. │1913.
───────────────────────────┼──────┼──────┼──────┼──────
_From British countries_ │ 24│ 1,011│ 1,100│
_From foreign countries_: │ │ │ │
Russia │ 4,167│ 2,579│ 461│ 1,778
Germany │ 5,837│ 8,786│ 1,669│ 50
France │35,149│30,449│33,969│33,149
United States │ 494│ 794│ 644│ 3,623
Colombia │ 2,037│ 4,909│ 4,552│ 3,725
Other foreign countries│ 454│ │ 158│ 315
───────────────────────────┼──────┼──────┼──────┼──────
Total: foreign countries │48,138│47,517│41,453│42,640
───────────────────────────┼──────┼──────┼──────┼──────
Grand total, oz. │48,162│48,528│42,553│42,640
───────────────────────────┴──────┴──────┴──────┴──────
───────────────────────────┬──────┬─────┬─────┬─────┬─────
│1914. │1915.│1916.│1917.│1918.
───────────────────────────┼──────┼─────┼─────┼─────┼─────
_From British countries_ │ │ │ 28│ 458│ 265
_From foreign countries_: │ │ │ │ │
Russia │ │ 7│ │ │
Germany │ 3│ │ │ │
France │12,592│1,878│1,666│ 632│ 596
United States │ 257│1,265│ 191│2,716│
Colombia │ 2,296│ 139│ │ │
Other foreign countries│ 40│ 59│ 79│ │ 362
───────────────────────────┼──────┼─────┼─────┼─────┼─────
Total: foreign countries │15,188│3,348│1,936│3,348│ 958
───────────────────────────┼──────┼─────┼─────┼─────┼─────
Grand total, oz. │15,188│3,348│1,964│3,806│1,223
───────────────────────────┴──────┴─────┴─────┴─────┴─────
[16]
About 7 per cent. of the Russian and one-half of the Colombian outputs
were sold to England during the war, as well as most of the Australian
and Indian production. Much of this metal was refined in the United
States.
According to J. E. Orchard[17], the commercial control (financial) of
the world’s output of platinum of 267,233 oz. of 1913 was divided as
follows: France, 74 per cent.; Russia, 18 per cent.; United States, 4
per cent.; British Empire, 2 per cent.; other countries, 2 per cent.;
whilst the political control (territorial) was divided as follows:
Russia, 93 per cent.; Colombia, 6 per cent.; other countries, 1 per
cent.
ASIA
INDIA
Traces of platinum and iridium have been noticed in association with the
gold obtained from native workings at Bonai City. The gold occurs in a
deposit of iron oxide, which forms the cementing material in a hard
stratum of quartz pebbles. The oxide is separated by pounding, and then
washed away to extract the gold. The proportion of platinum to gold is
probably less than 1 to 20.
Platinum occurs, associated with gold, in the gravels of the Irawaddy
River in Burma. A small quantity of platinum is obtained at Myitkyina by
the Burma Gold Dredging Company. During the years 1911–13, 152 oz. were
won by this company. In 1915 the output was 17·7 oz., and in 1916, 9·25
oz. In 1917, 4 oz. only were produced[18]. Owing to the cessation of the
golddredging operations at Myitkyina, Burma has ceased to produce
platinum, the quantity recovered during the year 1918 being only 0·31
oz.[19].
It has also been located with iridosmine in the auriferous gravels of
the rivers draining the slopes of the Patkoi Ranges, both on the Assam
and Burma sides[20].
AFRICA
RHODESIA
Platinum has recently been located in the Gwelo district, about 6 miles
north-east of Indiva siding, where it occurs in the great dyke of
norite, which is here about 4 miles wide. A. E. V. Zealley, the late
assistant Government geologist, made this occurrence the subject of a
special report[21].
The country rock is a serpentinized dunite. The deposit is capped by a
ferruginous siliceous gossan from 4 to 5 ft. wide, which may be traced
on the surface for about 100 ft., and is comparable to a fissure vein.
The gossan consists largely of hæmatite and chalcedony, with occasional
veinlets of copper and nickel minerals. Although the presence of
platinum in the ore could not be detected by panning, the possibility of
its occurrence on geological grounds was considered, and a sample of
concentrate from an unstated amount of ore was forwarded to the Imperial
Institute for analysis. The sample was found to contain platinum to the
amount of 1 dwt. 20 gr. per ton. A report on the further development of
this deposit is awaited with interest.
A sample of concentrate from an unstated amount of material from the
gem-bearing gravels of Somabula Forest, Gwelo district, was received at
the Imperial Institute from the Director of the Geological Survey of
Southern Rhodesia in November, 1918. On analysis this sample yielded the
following per ton: platinum, 3 oz. 12 dwt.; osmiridium, 7 oz. The
concentrate also contained a large proportion of gold. As shown by the
latest information available, the deposits, although undoubtedly rich,
appear to extend over a limited area. According to an analysis made at
the Imperial Institute, a sample of chromite from Southern Rhodesia
(Selukwe) contained 0·17 per cent. copper and nickel oxides, and a trace
of platinum[22].
H. B. Maufe[23] has stated that as the River Umtebekwe drains two areas
of ultra-basic rock containing chromite, it might be expected to contain
alluvial platinum, as well as gold, and, as a matter of fact, platinum
has actually been discovered in a reef in the Great Dyke (norite), at
the head of the Umtebekwe valley.
The presence of platinum was recently reported at Willoughby’s Halt, 12
miles south of Gwelo.
UNION OF SOUTH AFRICA
_Cape Colony_[24].—Platinum is present in varying quantities in the
copper-nickel deposits at Insizwa, situated in the Cape Province, close
to the boundary between East Griqualand and Pondoland.
The rock formation consists of a basin-shaped mass of intrusive norite,
averaging from 2,000 to 3,000 ft. in thickness, and lying in the shales
and sandstones of the Beaufort Series of the Karroo System.
The ore body consists of sulphides of copper and nickel, in association
with pyrrhotite, the minerals occurring disseminated near the basal
margin of the intrusive in olivine picrite. Gold and silver are also
present in small quantities.
The average copper and nickel contents in the ore are each about 4 per
cent., and the platinum content averages from 2 to 3 dwt. per ton, the
platinum being unequally distributed through the ore[25] p. 14.
It is not certain in what form the platinum occurs. It does not appear
to be present as sperrylite. In the opinion of W. H. Goodchild it may
occur in close association with the silver[25] p. 35.
Mining operations have been intermittently carried on here during the
last fifty years, the last exploratory work coming to an end in 1911.
Operations were, however, resumed early in 1920.
_Transvaal._—Small amounts of platinum and its allied metals have from
time to time been noticed in black sands from the battery “clean-ups” on
the Rand at Klerksdorp and other gold-mining districts, and platinum to
the amount of 2½ dwt. per ton is reported to have been present in
residual slimes at the Rietfontein mines[26]. A specimen, consisting of
about 85 per cent. osmiridium and 15 per cent. platinum, recently
received at the Imperial Institute, was stated to have been taken from a
compact shale, immediately underlying the banket reef in one of the
mines of the Klerksdorp district. In the large majority of the gold
mines, however, the platinum metals, if present, appear to exist in such
small quantities as to escape detection.
A series of samples of chromite from Kromdaal, near Rustenburg, showed
from a mere trace to 1 dwt. of platinum per ton, and one sample of
chromite from the Secocoeniland deposits showed as much as 1½ dwt. of
platinum per ton[27].
NORTH AMERICA
CANADA
The occurrence of platinum in Canada was first observed in 1862, in the
course of gold-mining operations on the Rivière-du-Loup and the
Rivière-des-Plantes in the province of Quebec[28] p. 210.
Since that time platinum has been found in a number of localities
associated with auriferous gravels, but the crude metal has only been
obtained commercially from the Similkameen district in British Columbia.
These deposits first attracted attention in 1885. All the workings are
alluvial, although the platinum has in several cases been traced to its
parent source.
_Alberta._—Platinum and gold in minute grains, closely intermixed, are
found in the North Saskatchewan River, near Edmonton. In 1918 certain
platinum occurrences were examined by the Munitions Resources
Commission, visits being paid to Fort Saskatchewan and the Peace River
district, in Alberta. These deposits, however, proved to be
disappointing. In the former locality, which was carefully tested by
drilling, the values of the samples obtained averaged less than 10 cents
in gold and platinum per c. yd. of gravel[29] p. 427.
_British Columbia._—Platinum, associated with gold, which is the
dominant metal, occurs in the Tulameen River and its tributaries, the
principal of which is Slate Creek, others being Cedar, Eagle, Bear and
Granite Creeks. The metal is present in small rounded grains, or
pellets. Chromite is often found intergrown with the platinum, olivine
and pyroxene usually occurring in association. The heavy minerals
remaining with platinum in the concentrate are titaniferous magnetite,
chromite and native copper. The platinum is sometimes magnetic, probably
due to the covering of the grains by small particles of magnetite[30].
The following analysis, according to G. C. Hoffmann, is representative
of an average sample of crude platinum from the Tulameen River:
Per cent.
Platinum 72·07
Palladium 0·19
Rhodium 2·57
Iridium 1·14
Osmiridium 10·51
Copper 3·39
Iron 8·59
Gangue (Chromite) 1·69
Owing to the presence of osmiridium in considerable proportion, the ore
is classed as “hard metal,” and on that account fetches a higher price.
Many of the richer placers have become exhausted, and work is now
carried on by a few individuals, principally Chinese, who work during
the summer months only. In some cases high benches, 50 to 100 ft. above
the creek bottom, are being worked. Much of the platinum and gold is of
a coarse texture, with a rough surface, and the latter is sometimes
found embedded in quartz. Nuggets are sometimes found encrusted with
chromite, and are thus liable to be overlooked. The deposits are
therefore not of great age, and the metals have not been transported
long distances from their sources.
Kemp is of opinion that the platinum is derived from pyroxenite dykes
cutting through peridotites, which outcrop on Olivine and Grasshopper
Mountains.
It is of interest to note that some diamonds and rubies have been
discovered with the platinum in the Tulameen deposits. They are of good
quality, but of small size, and occur in a matrix of dunite[28] p. 210.
American capital dominates the platinum industry in the district. In
1918, at the request of the Imperial Munitions Board, special
investigations in this area were undertaken by members of the Geological
Survey, and several prospecting bores were put down to bedrock. Full
reports of the work done are not yet available, but it is understood
that the results are considered to be promising, and to warrant further
examination of the district[29] p. 429.
Platinum was in 1918 discovered at Franklin Camp, near Grand Forks,
B.C., in the “Black Lead,” so-called, which is a mixture of augite,
75·13 per cent.; orthoclase and microcline, 17·06 per cent.; hornblende,
1·47 per cent.; and magnetite, 6·06 per cent., as determined by
microscopic measurements on a typical specimen, with accessory minerals,
chalcopyrite, bornite and apatite. A sample of chalcopyrite assayed 0·38
oz. crude platinum per ton. Samples of the “Black Lead” assayed from
0·02 to 0·17 oz. per ton[31].
At Burnt Basin, on the Mother Lode claim, an auriferous quartz vein
carries platinum, in amounts varying from a trace to 0·25 oz. per ton.
The quartz also contains chalcopyrite, pyrite, galena, sphalerite and
molybdenite[31]. Native platinum in small quantities has been found
associated with gold in the following localities: Tranquille River,
Fraser River, Rock Creek, Yale District, North Thompson and Clearwater
Rivers. It has also been reported to occur in a dyke across the Kootenay
River upon the Granite Poorman Mining Company’s property a few miles
from Nelson[32]. At Siwash Creek, in the Tulameen district, small flakes
of platinum, associated with chromite, often occur in shear zones in
granite. Dredging for gold and platinum is being carried on, on the
Peace River, North British Columbia.
According to J. B. Hobson the heavy concentrate produced on the
Consolidated Caribo hydraulic mine at Quesnel, contains, besides gold
and silver, platinum, palladium and osmiridium, one analysis giving a
total value of $3,873 per ton. The gold and silver being non-amalgamable
are probably included in particles of pyrite and galena, whilst the
platinum metals are found as minute grains or are enclosed in particles
of chromite and magnetite. A system of “under-currents” is being
installed to properly dress this concentrate[33].
In 1917 the recorded output of crude platinum from the placer gravels of
the Tulameen district in British Columbia was 57 oz., that for 1918
being 39 oz. For the five years preceding 1892, this district produced
on an average over 1,500 oz. per year.
_Manitoba._—Samples of gold ore containing platinum have been obtained
in the Star Lake district of south-eastern Manitoba[34]. Analyses of the
samples from different auriferous reefs were made by the Department of
Mines in 1917, and yielded platinum varying in amount from a trace to
0·1 oz. per ton. In addition to gold and platinum, the veins carry small
quantities of galena, zinc blende, pyrite, chalcopyrite and arsenopyrite
in a gangue consisting mainly of quartz.
Platinum is reported to occur in auriferous quartz veins in several
mines and prospects in Le Pas district; a picked sample of ore from the
mine of the Northern Manitoba and Development Company, assayed $49 gold
and $17 platinum per ton[35]. McCafferty’s Prospect, about 5 miles away,
contains platiniferous quartz.
_Nova Scotia._—According to E. R. Faribault in _Summary Report_, 1918,
Part F, of the Canadian Department of Mines, platinum has been found,
mostly in traces, in some of the old gold districts of Halifax county
and, lately, in the tungsten concentrates of the Moose River mines. So
far, all occurrences are in quartz veins in the lower quartzite and
slate formation of the gold-bearing series of the Atlantic coast. The
platiniferous mineral is supposed to be sperrylite, with which is
associated arsenopyrite.
_Ontario._—Sudbury is one of the few places where platinum is profitably
extracted from deposits _in situ_. The metal, which was first discovered
in this region in 1889, is found mostly in combination with arsenic, as
sperrylite associated mainly with chalcopyrite in the well-known copper
and nickel-bearing deposits of the district.
The origin of the ore bodies has not yet been settled. They are either
marginal deposits in, or off-shoot deposits to, a norite laceolith,
which has intruded sedimentary rocks, the ores consisting principally of
chalcopyrite, pyrrhotite, and pentlandite. Metallic platinum, gold,
silver and palladium occur in the ore, the last also, probably, as an
arsenide. The highest platinum content is associated with the highest
copper content; the highest palladium with the highest nickel. According
to Roberts and Longyear[36] the mean analysis of rocks of from sixteen
drill holes gave an average ore content of: copper, 1·11 per cent.;
nickel, 1·95 per cent.; silver, 0·223 oz.; gold, 0·022 oz.; and metallic
platinum, 0·0068 oz. per ton. The ore is principally worked for its
nickel and copper content, and yields a large proportion of the world’s
supply of nickel. The ore is first smelted at the mines, and a portion
of the low-grade matte so produced is then shipped to South Wales for
final treatment, the remainder being sent to the recently-constructed
refinery of the International Nickel Co., at Port Colborne, Ontario, and
to the United States. It was stated in 1903 that this matte contained on
the average 1·25 oz. of the platinum metals per ton of nickel content of
the matte, of which about 80 per cent. was extracted[37] p. 10. The
Victoria Mine, owned by the Mond Nickel Co., is stated to carry a high
percentage of the precious metals, as is also the Vermilion Mine,
although in the latter case the ore body is very small. In 1917 the
total output of copper-nickel ore from these deposits amounted to
1,506,828 tons, of which the Canadian Copper Co. raised 1,139,629 tons,
the Mond Nickel Co. 361,335 tons, and the Alexo Mining Co. 5,864 tons.
The nickel content of the ore of the Canadian Copper Co. was about 2·5
times that of the copper, whilst the ore mined by the other two
companies contained the two metals in approximately equal proportions.
The matte produced by the Alexo Mining Co. is smelted by the Mond Nickel
Co. According to the report of the Royal Ontario Nickel Commission, the
matte produced by the Canadian Copper Co. in 1916 was estimated to
contain 4,640 oz. platinum and 8,460 oz. palladium, corresponding to
0·10 oz. platinum and 0·15 oz. palladium per ton of matte, the
International Nickel Co. recovering in that year 1,093 oz. platinum and
257 oz. allied metals. This company is now reported to have improved its
methods of recovery. In 1918 the total matte shipment by the Canadian
Copper Co. is stated to have contained, among other precious metals,
8,677 oz. platinum and 13,016 oz. palladium[38].
According to information supplied by the Mond Nickel Co., their nickel
residues derived from the refining of the matte are taken over by
Johnson, Matthey & Co., Ltd. During the years 1915–18 the residues
disposed of were estimated to contain the following amounts of platinum
metals:
(In oz. troy.)
───────────────────┬─────┬─────┬─────┬─────
│1915.│1916.│1917.│1918.
───────────────────┼─────┼─────┼─────┼─────
Platinum │3,078│3,782│4,913│4,465
Palladium │5,474│ │ │
Iridium and Rhodium│ 973│ │ │
───────────────────┴─────┴─────┴─────┴─────
Messrs. Johnson, Matthey & Co., Ltd., have kindly supplied the following
figures of platinum-extraction from these residues:
Oz. troy.
1916 3,722
1917 4,719
1918 4,958
The British America Nickel Corporation, who are developing some large
deposits in the same district, are also erecting a refinery near Hull on
the Ottawa River. It is stated that they will employ the Hybinette
process of electrolytic refining, and expect to obtain a high recovery
of the precious metals[29] p. 425.
With gradual improvements in the refining process, and with the refining
of the whole of the matte produced, instead of a portion only, as at
present, it seems probable that the production of platinum metals by the
three nickel companies may in time exceed 10,000 oz. per annum.
The 1919 report of the Ontario Bureau of Mines shows that in 1918 the
International Nickel Co. treated 62,250 tons of matte for 650 fine oz.
of platinum, 787 oz. of palladium, and 473 oz. of metals of the rhodium
group. This cannot be used as a basis of calculation, as the proportions
are not constant.
On the Quinn claims, near the Crœsus Mine, Munro Township, is auriferous
quartz containing platinum. Five assays gave a platinum content of value
ranging from $180 to $1,800 per ton (with platinum at from $40 to $50
per oz.)[31]. The Abro Mine in the Timiskaming district in 1915 shipped
between 5,000 and 6,000 tons of ore, containing 0·03 oz. of palladium
and platinum per ton. The ore consists of pyrrhotite, chalcopyrite and
pentlandite, in a gangue of altered peridotite and serpentine[7].
_Yukon Territory._—Platinum occurs associated with gold in small
quantities in most of the tributaries of the Yukon River, notably at the
mouth of the Hootalinqua River, and in the River Lewis[37] p. 12.
NEWFOUNDLAND
Chromite derived from the serpentinized area in the region of Mount
Cormack, situated in the central part of the island, has been found to
contain small quantities of platinum[39].
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. │ Value
│(troy).│ 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.