Bulong Area magnesite deposits, Bulong Goldfield, Kalgoorlie-Boulder Shire, Western Australia, Australiai

Regional Level Types
Bulong Area magnesite deposits	Group ofDeposits
Bulong Goldfield	Ore Field
Kalgoorlie-Boulder Shire	Shire
Western Australia	State
Australia	Country

Altered serpentinites 2.25 miles east of town.

E.S. Simpson states, specimens were collected from the Bulong deposit from 1904. He states the area is an intimate complex of serpentine and gabbro, with the magnesite an intermediate matrix of the serpentine. Intruding the greenstones to the west are several large porphyry dykes, while to the east of the serpentine is a large area of coarse grained sediments, mostly pebble breccias. The western edge of Lake Yindarlgooda forms the eastern boundary of the magnesite bearing serpentine deposits. The serpentine consists of antigorite with actinolite and un-altered augite.

The main deposit trends north-south for 2.25 miles, covering 320 acres. Several smaller areas of magnesite in serpentine are found nearby, the main one 90 acres about 1 kilometre to the north.

The magnesite occurs in shallow veins up to 2 feet wide, often occurring in parallel groups. They have weathered less than the serpentine, and stand out as conspicuous white ridges, a few inches above the surrounding surface. Strike and dip of the veins is highly variable. The main deposit shows decomposed serpentine, with the magnesite making up much of the deposit.

The magnesite is almost pure white, dense or slightly porous, and extremely fine grained. Common salt, chalcedony, opal, and iron staining were the only impurities noted. The chalcedony can be 5% of the deposit, as milk white veinlets, or impregnations in the magnesite, at times lining cavities

Government geologist, F.R. Feldtmann, investigated the site in 1916. He states magnesite occurs as irregular veins in serpentine, probably formed from the alteration of the latter rock. It is largely free of lime, but contains moderate amounts of silica and iron. He states the amount of magnesite is un-certain but appears to be a very large deposit. The deposit is high purity at 90-95% MgCo3.

An un-official report in 1914 states it is a huge deposit of magnesite, running north-south for 4 miles, being pure white and a spectacular sight. The magnesite has patches of silica, iron and manganese, viewed as an impurity. Much gold has been found east and west of the deposit. Almost right at its eastern border the first battery was erected in the district, due to the amount of gold in the immediate area.

For several years magnesite was mined and exported from three quarries. 688 tonnes was mined in 1915, 10.5 tonnes 1916, and 73 tonnes in 1917. The shoots were short and irregular, and mining soon ceased.

An Adelaide syndicate first investigated the large magnesite deposits in 1914. From 1915, the Permasite Manufacturing Company of Melbourne took over. They opened three big quarries, covering 15 acres, immediately south of Magnesite Creek, mining 3000 tonnes of ore, of which around 1000 tonnes (according to the company in 1919) was sent to Melbourne over the four year period. This activity occurred from 1915 to 1917. GML 1Y and 2Y.

The company stated the enterprise was unprofitable from the start. They found it impossible to market the material overseas, and the limited Australian market was already serviced by Eastern States deposits. They had spent 6000 pounds to develop the Bulong deposits. Ore was sent via the Bulong to Kanowna tram line, but when this closed, there was no method to economically export the material.

The company was transporting raw ore, while government geologist, F.R. Feldtmann suggested a better option would be to burn the ore at the mine, losing half the weight, and thereby reducing cartage costs. The company forfeited the leases in 1920, due to non-payment of rent to the Mines Department. Member for Coolgardie, Lambert (surname) M.L.A. took over the leases, but little is done with them.

Magnesite was used at the time for refractory bricks in furnaces, boiler covering of asbestos, toilet preparations and in medicine.

William James McIntyre owns the leases in 1938, when B.H.P applied for forfeiture due to the deposits not being worked. The matter was settled out of court, but the result was B.H.P. took control of the lease. P.A. 1117Y.

B.H.P took over the leases totalling 400 acres (soon whittled down to 190 acres, then 48 acres by 1950). They were interested in using the material to line their furnaces at the Newcastle (N.S.W) steelworks. They explored the deposit only.

Clackline Refractory had the rights to mine magnesite at Bulong, paying B.H.P. a royalty. They sub-contracted this mining to the Bell brothers in 1950, and a trial parcel of 300 tonnes was sent to the company, located just east of Perth.

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References