The hill that made BHP

The ‘broken hill’ in NSW

Tony Webster FAusIMM(CP)

Introduction This presentation is NOT about the

geology of the Broken Hill region, or the structural history and genesis of the orebodies

If people are interested, I can present that in another talk.

I have tried to focus on aspects of the geology of the ‘broken hill’, that influenced the history and development of the Broken Hill Proprietary Company Ltd, and the ‘Silver City’ that developed next to its mine

The Palaeoproterozoic Willyama Supergroup in Far Western NSW

Location,

Willyama Supergroup

Location

Top 30 Stratiform Sedimentary Zn-Pb Deposits

Assoc Prof Steve Walters, CODES

The 1885 prospectus printed in Silverton – 25km from BH

From Bridges, 1920

The Prospectus

Charles Rasp, Boundary Rider (right)

Originally from Germany, – climbed the hill near the boundary of Mt Gipps and Kinchega ‘Run’s and collected

samples on the 5th of September 1883 – later assay revealed traces of silver.

Rasp is buried in the North Rd Cemetery in Adelaide. His mansion ‘Willyama’ is in the suburb nearby.

The story of his widow Agnes, and how she spent his fortune is a whole other story.

George McCulloch, Station Manager (left)

McCulloch married the widow of one of the men from Mt Gipps Station

He became a well known patron of the arts in London (the best collection of modern British Art in the world)

He died in London.

The Men that Made BHP

From Bridges, 1920

Both men died in 1907.

Guillaume Delprat, Engineer (left)

Dutch-born GM of BHP from 1899-1921 – moved the company from silver to iron and steel making and laid the foundations for BHP’s future success. Developed one of the earliest floatation processes (the Potter-Delprat process). In 1935 Delprat was the first recipient of the medal of the Australasian Institute of Mining and Metallurgy William Jamieson, Surveyor (right)

Was in Silverton surveying mining leases and bought in to the syndicate (3 shares – later sold two) – became the first Manager of the Broken Hill Mine. A director on the Melbourne board in 1906-26.

Harry Campbell, William Jamieson’s Aboriginal horse minder discovered the richest near-surface silver ore ever found at Broken Hill in 1885, while prospecting the southern end of Block 12 with his sledgehammer. This ore paid all of the capital costs of the mine development (e.g. Bridges, 1920). Wikipedia,

.

The Men that Made BHP

From Bridges, 1920

Delprat’s daughter Paquita married Douglas Mawson

The ‘broken hill’

Outcrop, Geology, Topography and Oxidised Zone.

The Outcrop

Views of the ‘broken hill’ in 1884 Taken from the southwestern end (NW side)

and looking northeast

Sources:

Upper photo: Broken Hill Outback Archive (courtesy of Brian Tonkin)

Lower photo from Bridges (1920)

Mrs W. R. Wilson and family on the outcrop, looking northeast over Block 14, 1885.

Note the dog at left. From Fischer (1970)

The Outcrop

‘Mine managers family’ (probably Mrs W. R. Wilson and family) on the highest part of the lode outcrop,

looking southwest over the BHP, 1885. Note the dog (again). From Kearns, 1996.

Views of the ‘broken hill’ in 1885 So much for the rugged, male-dominated

culture of early Broken Hill!

Single Quarters – c1890’s

View of the ‘broken hill’ from the south-eastern side - date unknown but probably

early 1890’s

The Outcrop

Broken Hill Outback Archive (courtesy of Brian Tonkin)

Single Quarters – c1890’s

View of the ‘broken hill’ from the south-eastern side - date unknown but probably

early 1890’s

The Outcrop

Broken Hill Outback Archive (courtesy of Brian Tonkin)

The Outcrop: Topography reflects the underlying geology

Topography, lode outcrop and open cut positions From Webster, 2004; 2006 & unpublished

BHP Mine 1, 2 and 3 Level Orebody Geology After Webster (2004; 2006)

Prominent features of the outcrop reflect structures in the orebodies The Outcrop: Topography reflects the underlying geology

The Topography of the Hill Contour Plan of Broken Hill c1885 – with original leases.

Sketch of the Broken Hill settlement (now Delamore St) in 1885 by Surveyor, W R Thomas (from Kearns, 1996)

Track will become Argent St

Pre-mining topographic contour map of the ‘broken hill’ Constructed from early surveys (mainly Andrews, 1922 and Gustafson, 1939)

Contours are at approx 3.3m intervals (10 feet)

Rocky bluffs = ---------

From Webster, unpublished

The Topography of the Hill Contour Plan of Broken Hill c1885 – with original leases.

Sketch of the Broken Hill settlement (now Delamore St) in 1885 by Surveyor, W R Thomas (from Kearns, 1996)

Track will become Argent St

Rocky bluffs = ---------

From Webster, unpublished

In 1885, it wasn’t at all certain if the hill would come to anything.

A newly graduated 19yo chemist and assayer, W. H (‘Bill’) Corbould, would often stroll up the hill with a friend …..

‘If ever it turns out any good, we can say we sprayed it in its infancy’

In the 1920’s, Corbould consolidated the Mt Isa

field and founded Mt Isa Mines (MIM)

Photo & story from Hore-Lacy, 1981

The Topography of the Hill

and occasionally they’d piss on it.

Images: Left, Australian Museum; right, Chapman Collection

The early wealth of BHP was the result of the rich supergene (oxidised) zone below the surface of the hill – particularly on the BHP Mine 1 and 2 Levels.

Modified after BHP (unpublished); Jamieson and Howell, (1893), and Webster (2004; 2006)

Geology - Supergene-enriched Oxidised Zone

Images: Left, Australian Museum; right, Chapman Collection

The early wealth of BHP was the result of the rich supergene (oxidised) zone below the surface of the hill – particularly on the BHP Mine 1 and 2 Levels.

Plan of 212 foot level

Silicious Iron Ore

Kaolin & Iron

Silicious Carbonate of Lead

Silicious Iron & Kaolin

Carbonates Oxidised Ore

Oxidised Ore

Kaolin

Kaolin

Silicious Ores

Carbonates

Silicious Ore

Carbonates

Modified after BHP (unpublished); Jamieson and Howell, (1893), and Webster (2004; 2006)

Geology - Supergene-enriched Oxidised Zone

The Geology of the ‘hill’

From Webster, 2004; 2006

The ‘broken hill’

Surface Infrastructure

ML 12 ML 13 ML 11

Surface Infrastructure of the Broken Hill Proprietary Mine 1892

Mining and treatment infrastructure – on the flanks of the hill

Development of the mining infrastructure was very rapid once the field was proven

Photo sources: BHP and Kearns (1996)

ML 12 ML 13 ML 11

Surface Infrastructure of the Broken Hill Proprietary Mine 1892

Mining and treatment infrastructure – on the flanks of the hill

Development of the mining infrastructure was very rapid once the field was proven

And it wasn’t just mining infrastructure…..

Photo sources: BHP and Kearns (1996)

• Geotechnical issues (wide stopes with poor underground support) led to the removal of mining infrastructure from the flanks of the hill and the

• Adoption of the square set timber system of stope support in 1888 (from the Comstock Lode in Nevada - North Forest Products originally formed to supply mine timber)

The ‘Creeps’ – Geotechnical issues lead to a rethink

Square set stoping was still in use at North Mine until just before the North Mine closed in 1993.

Hydraulic fill was later perfected at the South Mine Central Mine mill wrecked by ‘creep’ in 1905. From Blainey (1968)

The Smelters

BHP Smelters in in 1894. Source: Alban Lynch, talk to AusIMM Melbourne Branch, Feb 2008

Originally four smelters in BH

• Block 14, • British, • Central and • BHP - BHP’s the biggest in Australia

BHP had a small silver refinery in Port Pirie and had bought the small British Broken Hill smelters there in 1892

The Smelters

Early 1890’s: decision made to move smelters to the coast

(depletion of oxidised ores, floatation, cheaper fuel,

transport etc).

All had closed by April 1898.

BHP smelter, Port Pirie, South Australia, 1906

From Blainey (1968)

The Port Pirie smelters needed ironstone flux.

The nearest source was directly across Spencer Gulf, at an ironstone hill called the ‘iron knob’.

BHP acquired the lease.

The City of Broken Hill

Caldwell’s impression of Broken Hill (later Delamore St) in late 1884. From Worner & Mitchell (1983)

1885 sketch of Broken Hill by J. Renowden (from Kearns, 1996).

Images of Delamore St, Broken Hill – from Google Maps

Development of the City of Broken Hill

Eastern end Argent St and Delamore St, 1886 (from Solomon, 1988)

Caldwell’s impression of Broken Hill (later Delamore St) in late 1884. From Worner & Mitchell (1983)

1885 sketch of Broken Hill by J. Renowden (from Kearns, 1996).

Images of Delamore St, Broken Hill – from Google Maps

Development of the City of Broken Hill

While the mining infrastructure developed on the flanks of the hill, the town grew on the alluvial flats to the north.

Development of the City of Broken Hill

Development of the City of Broken Hill: The geology controlled the ML orientation – which influenced urban layout

Google Earth image of the central part of Broken Hill

Development of the Deposit

1890’s – 1930’s

Longitudinal section of the Broken Hill mineralised system (2004)

The Topography Reflects the Underlying Geology

Lost to erosion

Only about 3 million tonnes of mostly low- grade mineralised rock

lost to erosion

Modified from Webster, 2004; 2006

Metal Production 1883-1994 (Pasminco Ltd, unpublished data, 1995)

• 19.3 mt Pb,

• 16.6 mt Zn,

• 28.7 million kg Ag,

• 23 t Au (a bi-product of base metal mining).

The Potosi & Silver Peak orebodies are probably the continuation of the main

lode system

By the late 1930’s it had been recognised that the deposit consisted of multiple ore lenses.

Eventually there were at least nine spatially associated,

flattened & ribbon-like stratiform orebodies defined.

The Deposit – Multiple Ore Lenses

BHP Mine

Steep north and south plunge not fully recognised in the early days.

• Others pegged the leases to the south and far north of the BHP ground

• To facilitate the rapid development of the field and possibly to share some of the risk, BHP floated off separate companies based on their northern leases (these mines ultimately passed to other owners)

2 km

3 Lens

3 Lens & 2 Lens extend for most of the length of the field, a distance of over 8.5 km & until recently accounted for most of the production from the field.

The Deposit – Multiple Ore Lenses

BHP Mine

Subsequent deeper mine development was to prove that most of the tonnage of high grade ore was in the down-plunge extensions to the south and north

Modified from Webster, 2004; 2006

2 km

2 Lens

3 Lens & 2 Lens extend for most of the length of the field, a distance of over 8.5 km & until recently accounted for most of the production from the field.

The Deposit – Multiple Ore Lenses

BHP Mine

Modified from Webster, 2004; 2006

2 km

A Lode Lower/Upper/Southern, Western AL/Western Min, 1 Lens

Several lesser-mineralised horizons predominate in the SW & now account for most of the production of the field.

• A Lode Upper (ALU), • A Lode Lower (ALL), • 1 Lens Upper (1LU), • 1 Lens Lower (1LL) immediately above 2L.

Southern A Lode lies in the same stratigraphic position relative to BL as ALU but is a distinct occurrence to the

southwest, and

Southern 1 Lens is a separate ore horizon occupying the 1L stratigraphic position in the southwestern Perilya Mine.

Probably more closely akin to B Lode,

The Deposit – Multiple Ore Lenses

BHP Mine

Modified from Webster, 2004; 2006

2 km

B Lode (lies at the top of the succession of lesser mineralised horizons).

Several lesser-mineralised horizons predominate in the SW & now account for most of the production of the field.

The Deposit – Multiple Ore Lenses

BHP Mine

Modified from Webster, 2004; 2006

2 km

‘C Lode’ & 4.5 Mineralisation

The 4.5 Mineralisation lies outside the Hores Gneiss. C Lode Mineralisation is mostly derived from B Lode

The Deposit – Multiple Ore Lenses

BHP Mine

Modified from Webster, 2004; 2006

Longitudinal section of the Broken Hill mineralised system – looking northwest

Why did BHP leave Broken Hill?

BHP finally closed its mine in 1939 after spending several years scavenging ore during periods of favourable metal prices.

It withdrew from Broken Hill in 1940.

Broken Hill South Ltd later acquired the leases and extracted a large volume of remnant ore (largely as a result of the perfection of the hydraulic fill process). In 2011, the new Rasp Mine (CBH Resources) is developing a low grade orebody

in the former BHP lease area

By 1909 the BHP mine was hemmed in, with depleting ore stocks.

Delprat recognised that the mine was dying

Longitudinal section of the Broken Hill mineralised system – looking northwest

Why did BHP leave Broken Hill?

BHP finally closed its mine in 1939 after spending several years scavenging ore during periods of favourable metal prices.

It withdrew from Broken Hill in 1940.

Broken Hill South Ltd later acquired the leases and extracted a large volume of remnant ore (largely as a result of the perfection of the hydraulic fill process). In 2011, the new Rasp Mine (CBH Resources) is developing a low grade orebody

in the former BHP lease area

By 1909 the BHP mine was hemmed in, with depleting ore stocks.

Delprat recognised that the mine was dying

Legacy of the ‘Big Mine’ in Broken Hill

Remnants of BHP’s Presence in Broken Hill

Chimney of the first camp (Jamieson's)

The leases of the Broken Hill Field (now consolidated mining leases)

From Bridges (1920)

‘Proprietary Square’ – the BHP senior staff housing area. Delprats house still stands (with the Billiard Room he added after becoming hooked on the game) – now the Perilya Social Club

Remnants of BHP’s Presence in Broken Hill

Image of Proprietary Square, Broken Hill – from Google Earth

Remnants of BHP’s Presence in Broken Hill

The black slag dump that dominates the skyline

The foundations of the ‘New’ Mill

Delprat’s Shaft (with later headframe)

The office site is now under the rail yards at the bottom end of Sulphide St – built during the war to

tranship freight from the standard gauge to the narrow gauge Silverton Tramway to SA

A lingering legacy is the deep-seated hatred of the company by the locals – BHP won most of its battles

with the unions

Images surviving features if the BHP Co Ltd’s infrastructure at Broken Hill – from Google Maps

What is left of the ‘hill’? - Browne Shaft

Webster (2004; 2006)

Browne Shaft lookout cutting Shows Mn carapace over 3 Lens

What is left of the ‘hill’? - Browne Shaft

Webster (2004; 2006)

These principles of mining infrastructure placement still apply today. Only the scale has increased

If you think that this is all irrelevant history and that it doesn’t apply to the modern world, think again

Is this stuff relevant?

These principles of mining infrastructure placement still apply today. Only the scale has increased

Is this early view of the Hub and Mt Whaleback from Newman all that different to Broken Hill in the 1890’s? Source Eckhart (1998)

If you think that this is all irrelevant history and that it doesn’t apply to the modern world, think again

Is this stuff relevant?

There is another hill that features very prominently in the history of BHP – Iron Knob in South Australia

But that story is for another day.

Last Word