Ajax Gold Mine, Norseman, Dundas Shire, Western Australia, Australiai

Regional Level Types
Ajax Gold Mine	Mine
Norseman	Town
Dundas Shire	Shire
Western Australia	State
Australia	Country

The former Ajax Gold Mine is south of the Bullen mine. Activity at the site relates to two periods, the 1890's and late 1930's.

Located approximately 3kms east-south-east of Norseman.

Information about the mine was found initially from 1896, stating they had uncovered the cap of the reef. Little other early information is provided, although brief notes are made that it was active across the period to 1899.

A report in 1899 stated the lease was 12 acres, owned by a local syndicate, and there was a main shaft, another shaft to the west down to 30 feet, and two shafts at the north-west corner of the lease at 12 and 16 feet. The oxidised ore went to 35 feet below the surface, then it changed to sulphides, and was highly mineralised.

In 1904, Schertsinger (or Shertzinger depending on the source), Motherston and party sank a shaft to 34 feet on a lode 4 feet wide, showing gold, large amounts of galena, and pyrite. However, later in the year the lease was under exemption.

Then Central Norseman Gold Corporation NL, announced in 1939, the sinking of a new shaft to be called the Ajax, somewhere near the old workings. They intersected the Mararoa Reef at 2,200 feet.

By 1943 it is noted that work at the shaft had stopped. This was further confirmed by later information. Proving what we think as modern problems in fact has always been happening, complaints were made that school aged children were vandalising the abandoned site. Windows had been smashed, electrical switches pulled out, and insulators broken. They had also risked their lives by interfering with the cyanide vats. The headframe was removed to another shaft in 1949.

Central Norseman Gold Corporation has not released much information to the public in recent decades. As a company that has operated at Norseman in one incarnation or another since the 1890's, I guess it feels there is no need. There is some indication the Ajax mine was active in the 1990's and early 2000's. At the time of writing 2015, it is inactive.

The host rock is the Woolyeenyer Formation of tholeiitic basalt flows striking north north-east, and dipping 50 degrees west. In the southern area of the Ajax workings, there is much felsic intrusive bodies, in some areas constituting the dominant rock form. Overlaying this is the Bluebird flow sequence. The lower margin, or first flow is fine grained hornblende-plagioclase-amphibolite, 2 metres thick, grading to coarse grained 5 to 20 metres zone of plagioclase material.

Level 10 of the mine accesses the Mararoa Reef. The host rock here has been metamorphosed to hornblende-plagioclase-amphibolite, and actinolite-chlorite rocks. Intense wall rock alteration, and low grade (0.5 g/t) gold mineralisation was confined to ductile or brittle ductile shear structures. Alteration consists of an outer zone of actinolite-hornblende-plagioclase-epidote, middle zone of hornblende-actinolite-biotite-plagioclase, and inner zone of dominant biotite as well as some quartz-actinolite-plagioclase or calcite. Actinolite shows as fibrous rosettes in quartz veins. The epidote is fine grained.

The Ajax mine accesses three vein systems, which reach widths of up to 10 metres. The Crown Vein strikes for 2.5 kilometres, consisting of 5 major ore bodies hosted by the A, B, and South Crown Faults. The ore bodies plunge south-east.

The second vein system is the Mararoa. This is hosted by the high magnesium Butterfly Dyke, striking 4 kilometres, with 4 major ore bodies, plunging also south-east.

The third is the Norseman vein systems, which runs parallel to the Mararoa, and as with this system, ore bodies are restricted to north north-east striking segments of the veins. The E Fault cuts the Mararoa and Norseman veins at the southern end of the Ajax workings, and is the southern limit for economic gold in these giant vein systems.

Sulphides are locally abundant in the wallrock adjacent to the veins. Pyrrhotite dominates the alteration envelopes, and pyrite dominates the quartz veins. Veins within the shear zone are 90% quartz, but with subordinate calcite, actinolite, pyrite, scheelite and schorl.

At the microscopic level, euhedral pyrite grains within the quartz are fractured and infilled with galena, and gold tellurides hessite, altaite, petzite, sylvanite, and native gold. Galena, sphalerite and gold are localised along the grain boundaries. At the E Fault at the southern end of the workings, an investigation in the stopes found galena, sphalerite, sericite, chalcopyrite, tellurides and gold, intergrown along fractures in veins.

References

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