Butcher Bird Mine (Atkinson's Find), Mount Jackson Goldfield, Yilgarn Shire, Western Australia, Australiai

Regional Level Types
Butcher Bird Mine (Atkinson's Find)	Mine (Backfilled)
Mount Jackson Goldfield	Ore Field
Yilgarn Shire	Shire
Western Australia	State
Australia	Country

An historic gold mine.

The Atkinson family founded the Mount Jackson Station, which incorporated a vast area north of Koolyanobbing. The ruins of the original stone homestead can be found along a track west for about 10 kilometres from the Bullfinch-Evanston Road. The track passes the Allen's Find gold mine.

The Atkinsons pegged a number of leases on the Mount Jackson goldfield in the 1890's. This particular mine is at the northern end of the goldfield, less than 50 metres west of the intersection with the Bullfinch-Evanston Road, with the Windarling mine haul road.

It is an east-west striking reef, that in 1911 very little work had been done on it. The relatively substantial mullock at the site (compared to many other locations here which are often no more than an old shaft), show some prospector activity since that time.

In 1911, there were 13 leases at the site, but only 1 was being worked, which was the original discovery. The reef strikes east-west, and dips 30 degrees north north-west. A large ore body showing gold and galena freely, with well defined walls. The west end is cut by a north-west to south-east striking cross reef, 6 in to 1 foot wide, of considerably lower value gold than the main reef. By 1914, the shaft was down to 150 feet, passing the footwall near the bottom. From this was an irregular network of workings. The site had a small battery with water supplied by the Marda Dam.

The reef is large and low value. The country rock is decomposed dolerite, more acid than Allen's Find, and more basic than the Great Unknown Mine. Near the footwall, at the 75 foot level,
is a patch of iron arsenates containing scorodite and pharmacosiderite. The former is common pale greyish green granular irregular shaped masses. The pharmacosiderite is well formed bright emerald green crystals 1-4mm diameter. They filled cavities in quartz once holding arsenopyrite, or are embedded singularly, or in groups in the centres of scorodite masses. The crystals are simple cubes, or some half the corners of the cube truncated by faces of the tetrahedron, or by a combination of both. Interpenetration twins resembling fluorite is common. Specific gravity of both scorodite and pharmacosiderite at the mine is 2.55.

Pyrite is found as small cubic crystals and pyritehedrons in solid quartz which has been protected from weathering. Gold is fine to moderately coarse particles freely distributed and attached to the side of the quartz cavities where the arsenopyrite once was. It is also found embedded in unweathered arsenopyrite, and in quartz.

Gold has been formed by the diversion of the solution flow around the curvature of a fissure. The shoot of gold is at the eastern arm of a pitching syncline in the reef.

References

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