“The Most Important Mining Discovery of the Last Decade”

Below is an exceptional article from the Queenslander of 1924.  A remarkable record so soon after the discovery of Mt Isa and replete with the excitement of such a significant discovery.  At the time of writing a mere 145 tons of ore had been shipped. The original has been transcribed from the Queenslander newspaper, where the ink has been absorbed by the newsprint making transcription locally difficult. Some editorial licence has been taken and minor alterations, including conversion into g/t, have been made and images added.

Prospector John Campbell Miles (left) in 1924 with Walter John Davidson (Current Minister Scott Stewart’s great-grandfather), Will Purdy, S Boyce, and EC Saint-Smith, State Geologist.


Saturday, January 26, 1924

In 1918 I travelled by Argylla and West Leichhardt to Lagoon Creek – 18 miles west of West Leichardt Telegraph Station returning to Cloncurry by a little east of the Sulieman Creek-Camooweal railway survey, via Bushy Park and Duchess. My journey was made to locate Mica deposits on Mica Creek, and returning from these I passed the Mount Isa field at a distance of a few miles, and on the wrong side of the range, as a hundred other men have done. For, as John Forrest said in explanation of failing to see gold although hw was on the Coolgardie field 23 years before their discovery: “A man gets what he’s looking for, and Forrest was looking for pastoral country.


There is little doubt now that Mt. Isa is Elliott’s secret. Elliot, the discoverer of Mt. Elliott copper mine told 20 years ago of a discovery of rich copper lodes on the West Leichhardt. Then he died in Cloncurry Hospital, and for years after men searched the West Leichardt region for Elliott’s secret, and never found it. The galena of the Mt. Isa field is very fine-grained, and a novice in silver-lead might mistake it for glance.

The searchers for Elliott’s Secret walking below the heights of iron coated with manganese that mark generally the ore deposits of the Mt. Isa field did not explore them, because they looked for the green efflorescence of copper-salts; and a gallon of that, can paint half a mile of quartzite to look like the map of Ireland. The little greenness showed in the out crop of Mt. Isa attracted John Campbell Miles and his mates early in 1923; and once examination began the field could not be missed. For five miles north and south by a mile wide, the outcrops oi the field are wide, rich, and. persistent in length over the central area of three nines.

For a mile on either end of this the ore runs are still persistent and rich but narrower; hard ore in soft kaolinized country which the jasperoid and cherty rock of the surface become under cover. The silver-lead ores are inter-bedded with the strata, and these jasperoid outcrops in the lode channels are almost invariable indications of the ore bodies.


The central area of the field—three miles by one, already mentioned—represents a great crush zone in which the strata hare been so buckled as to form, in places, almost a semi-circle. In these openings of -the stratification solutions have deposited 1 silver-lead, not merely filling the fissure, but also replacing the clay slates and invading and altering the surrounding country. Generally, the ore deposits are very uniform in width, and that for great lengths. The coach route from Duchess to Camooweal passes the field at a distance of a mile and railway connection with Duchess can be got in 50 miles or so over fairly easy country.

This line will suffer little delay in construction, the Government being satisfied of the great possibilities of the field. Meantime the road communication can be shortened from 64 miles to 56 by making a track nearer the river head to a more direct line to the Pot Holes. At this point, a well, bottomed in December, on 1300 gallons water per-hour. The present water supply of the field is Lagoon Creek well. From this well, an enterprising Australian, aged 14, carts the fields supply, and sell, it at the rate of 2/ per 4-gallon petrol can. While i was there the 14-yearold water king suffered competition — a rainfall of about an inch. Annual rainfall from 16 to 25 inches: a little of that falling in October and November. but the main supply arriving in from December to March.

Mt. Isa field as a series of high ridges of clay-slates and shales sandstone, cherts, and Jasperoid, with heavy out crops of manganiferous iron. The stony ridges of the field are dotted with spinifex, and the timber is poor:  Gidyea, blood wood lancewood, turpentine, beefwood and coolabah. On the evidence of Dr. Jensen and other geologists, the Cloncurry series should be pre-Cambrian, and that belief is supported by Mr. E. C. Saint Smith. Government Geologist, who places the “finely, luminated biscuit-coloured shales of Mount Isa with the shale of Wondai” which Mr. Saint Smith considers as “fairly certain to belong to the Brisbane Schists”.

Harald Ingemann Jensen, 1906 Photographer: Sidney Riley, Queen Street, Brisbane.


The general trend of the Mount Isa de-posits it north and south, underlying; west. The limit of value for payable shipment of ore (freight to the railway at Duchess alone is £4 per ton) is about 40%, lead and 930 g/t silver; at least, that is the limit on the gougers’ expensive system working. Gelignite costs up to 12/9 a packet, and other mining necessities are relatively high. It is a field located by man with little or no working capital, and it is cheering to know that in the inevitable transfer of the field to companies the pioneers are getting good consideration for their holdings. Up to the end of November the field has despatched 145 tons ore averaging lead 60.1% and silver 1,240 g/t; and a little more than a trace of gold, although many assays on the Out on Her Own gave gold in pennyweights.

On a score of leases export quality ore is at grass and bagged waiting shipment, and on most of the leases the absence of good grade is the exception.


The Silverina & Crystal

Beginning at the south end of the field the Silverlena shows 2ft. of carbonate ore of shipping value is a shaft 53ft. deep.   In places, covered by alluvium, these southern veins are continuous to the Crystal, which has opened three deposits that promise the production of much high grade ore—cerussite and galena. An average sample of the Cerussite, in the southern open cut, near the centre of the lease, gave 8,100 g/t. silver. Eleven tons despatched bulked 62.1%, lead and 220 g/t. silver, and the cut is not the limit in width of the ore body, as the hanging-wall country – an ocherous clay-slate -shows large bunches of carbonate and galena. The average of assays show 55% lead and 2,200 g/t silver, excluding two samples of green carbonate, yielding 62.30% lead and 61,000 g/t silver, and 62.40%, lead and 83,600 g/t silver

The Laguna

To the south of the Crystal and Laguna has despatched ore bulking 59%. lead and 33g/t silver. The ore in the outcrop was chiefly cerussite, and bulked 63%, lead and 3,000 g/t. silver. The individual veins are small, but so frequent through a great width of ore channel as to promise good tonnage of payable ore.

Orr’s Prospect

Orr’s Prospect lease shows a shaft 46ft. deep, with a good seam of carbonate ore 9in. wide apparently one of the series worked in the Rio Grande, adjoining it on the north.

Rio Grande

In the Rio Grande four cuts have been put in over a length of two and a half chains, and a width of a chain and a half, showing seams of earthy carbonate and cerussite up to a width of 4ft. Parcels of ore shipped bulked 65%, lead and 1,100 g/t silver; 50%, lead and 1,054g/t silver; and 54% lead and 1,457 g/t silver. Sinking and crosscutting must pick up other veins not showing in the cuts but outcropping on the west of them.

Even Break

Adjoining the Rio Grande on the north is the Even Break, which has opened up good veins of ferruginous carbonate of lead between siliceous ironstone, with yellow shales on the foot-wall. Fifteen tons from a gossan outcrop working bulked 50% lead and 310g/t. silver, and 7 tons bulked 54%, lead and 992 g/t silver. This lease must have the extension of the Rio Grande ore-occurrence, and also the southerly continuation of the great ore channel proved in The Out On Her Own.

Out On Her Own & Black Rock

The feature of this property is a hill rising 466 ft. above the general level of the country, and capped by a wide black outcrop, coated with manganese, and extending into the Black Rock lease to the north. The black outcrop is apparently on the hanging wall of the ore channel, which is shown by open cuts on the easterly slope of the hill to be not less than 300 ft. wide. At the summit a shallow open cut exposes 9ft. of banded ore bulking 44% lead and 1,200g/t silver, the ore being mostly galena. Other samples gave 62%, lead, silver 3,400 g/t and gold 3 g/t; lead, 48.40%., and silver 920 g/t; lead, 71.45%, gold 3.2 g/t, and silver 2,700 g/t; 58.76% lead, silver 434 g/t; 54.13% lead, gold 2.3 g/t, silver 1,705 g/t; lead 28.75%, silver 9,600 g/t.

A tunnel into this hill will give nearly 356 ft. of backs of the ore occurrence, bulking 44%. lead and 1,220 g/t. silver and there can be little doubt of the Out On Her Own becoming a producer of high grade ore in quantity: The Black Rock has two open cuts, exposing the northerly extension of the Out On Her Own lode, and the prospectors have despatched ore worth from 44 to 62%, lead and up to 1,200 g/t silver. The silver content of the ore at surface is not as high as southerly—the average of all assays being 54.5%, lead and 496 g/t silver. When a little copper shows in the ore bodies of the field, silver contents are higher, and it is noticeable that zinc is entirely absent, not a trace being discovered in any of the samples assayed.

Durban Angel

Between the Black Rock and the Durban Angel, to the north, a small lease pegged across the ore channel and not with it, interposes. The Durban Angel shows a great iron cliff showing a few seams of ore at its base. Beyond it to the north are the Central, Middle Ridge. Racecourse South, and Grande, and south of, and adjoining the Racecourse and north of the Grande, is the Mt Argyle.

The Racecourse

The Racecourse – so called because of the rough amphitheater surrounding the main outcrop – is apparently in the centre of the crush zone. The buckling of strata has been intense, and an open cut of 40ft. long and 30ft. deep at its maximum has been entered – from the north, and shows a well defined anticline. The ore is in saddle formation, the central formation 8ft. wide and the western leg of about the same dimension. The ores are crystals of lead carbonates, sulphates, cerussites, and galena of very fine grain, and a little pyromorphite. At the southern end of the cut, a dark powder by the solid ore gave values of 62.76%, lead and 4,100 g/t silver; and a dark earth in the vugs along the legs of the saddles bulked 56%. lead and 1,085 g/t silver. This ore occurrence will be one of the best, of the five distinct lodes of the field, and the Mt. Argyle adjoining it on the south has the extension, of this big rich lode beyond doubt.

Around the Racecourse on the east are the Gympie Savage, Gairns claim, and others, with sufficient development to prove the ore channel at this point to be much wider than in the Racecourse lease itself. It is all apparently the one lode channel from the Mt. Isa North through the Racecourse, Mt. Argyle, Durban Angel, and Black Rock, to the Out On Her Own and Even Break, a distance of yearly three miles. North of the Racecourse are the Barrier and the Flying Pig, and then Mt. Isa—the discoverer’s first claim.

Mt Isa Leases – East and West

The Mt. lsa Leases show a big outcrop of chert, carrying numerous veins of lead carbonate, all with the characteristic surface blackened by manganese. About 20 ft. wide of lode matter shows dipping into the ridge westerly, and west of this the lode channel shows 2 1/2 chains wide, with a strong band of gossan dividing; the formation near the top of the ridge Mr. Saint Smith bulked 6ft. of this for 48%, lead and 4,976 g/t. silver. To the east of the Mt. Isa development on the Myra claim shows the occurrence of important veins below the main outcrop; and the Ethel claim, on the southwest corner of the Mt. Isa lease, shows good ore in an entirely new formation; so that lode channel widths have the prospect of being far greater than present developments hint at.

Sunrise and Leichardt King

Due north and north-east of the Mt. Isa leases for nearly a mile the flat country is covered by rock spoil and alluvium, and costeaning would probably locate the southerly extensions of the ore deposits now worked further north of the Sunrise and the Leichhardt King. On the Sunrise carbonate ore outcrops continuously for 86 yards, although the veins are comparatively small. In the Leichhardt King, north of the Sunrise, ferruginous lead carbonate is being mined, the country rock being day shales with limonite bands interbedded. Ore shipped from this point bulked 65%, lead and 992g/t silver, and from the cut two chains north 63% lead and 992 g/t silver.

Black Star

The western series of ore channels of the field have their show place in the Black Star, about 400 yards to the west of Mt. Isa and Racecourse line.

The Black Star has for its main feature a cherty outcrop greatly contorted, heavily stained with manganese and iron oxides, and carrying seams of lead carbonate on both hanging and footwall aides of the outcrop, which rises 90ft. above the general surface. At near the top of the outcrop carbonate ore low in silver bulks 60% lead ; and at two chains south of the north boundary, and on the footwall side of the outcrop; which is about 20ft. wide, a seam of ferruginous carbonates 4ft. wide bulks 60%, lead and. 220g/t silver. A paddock of ore broken by the central outcrop bulks 65%. lead and 49,600 g/t silver. Roughly, it is difficult to find a yard on the lease which does not carry lead carbonate, and as ore runs has been found to the west of the outcrop, and as far east as the eastern boundary, it is patent that the Black Star holds a very large deposit of silver lead.

The Ibus & Starlight

The Ibus, adjoining the Black Star on the north, generally fits the description of the Black Star, of which it is a continuation, carrying the central outcrop, and the veins to the east and the west and many gossan blows bearing lead values. On the north-east boundary of the Ibus is the Starlight, working several veins of ferruginous carbonate for 56% lead  and 210 g/t silver. Cerussite from a vein traceable for several chains yielded 44% lead and 430 g/t silver, and a picked-sample from the vein have 202,150 g/t silver.  This, sample was sulphide, with a little carbonate of lead.


Shortly these. are facts of, this new silver-lead field which. Mr. Saint. Smith, Queensland Government Geologist, regards as “the most important mining discovery of the last decade.” He might go further, and say that there has been no silver-lead field as rich and wide and as persistent in length since Broken Hill-and Broken Hill’s surface ores were poor-low in lead and very low in silver. Here on Mt. lsa are five distinct parallel ore channels – with the northern and southern ends of the fields good enough for export and the centre of ore occurrence most important in future pro-duction on a great scale. With very few, exceptions the leases I visited were all on payable ore even, under present conditions, and these are wasteful of effort and money, as already shown. The discoveries have put heart into prospectors starved for years by a low copper market, and on the encouragement of Mt. Isa the hardy optimists of Cloncurry will comb the great area of ancient strata in the region now proved richly metal bearing.

New encouragement will surely come from the development of the Black Star, Ibus, Mt. Isa, Racecourse, Mt. Argyle, Out On Her Own. Black Rock, Even Break. Crystal and Rio Grande; and probably also from many other shows that at the moment have little promise in comparison with the properties herein before mentioned.

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The Author

Randolph Bedford (born George Randolph Bedford) (27 June 1868 – 7 July 1941) was an Australian poet, novelist, short story writer and Queensland state politician.

Randolph Bedford (born George Randolph Bedford) (27 June 1868 – 7 July 1941) was an Australian poet, novelist, short story writer and Queensland state politician.    In 1917, Bedford entered the Queensland Legislative Council, on a platform to secure its abolition (which occurred in 1922). In 1923, he was elected as Labor candidate to the Queensland Legislative Assembly for Warrego, a seat which he held until his resignation in 1937 to contest the Division of Maranoa in the Australian House of Representatives.  Bedford was defeated but was again elected to his old seat in the Queensland Legislative Assembly.  He had an impatient streak and was not elected to cabinet. He was an ardent Protectionist, and decried the way the wealth of Australia was exported to pay for shoddy goods which could have been produced locally.


Rodney G. Boland, ‘Bedford, George Randolph (1868–1941)’, Australian Dictionary of Biography, National Centre of Biography, Australian National University.

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