Bronzewing enters production

The booming gold industry in Australia has spawned a series of major discoveries in recent years, one of the better ones being the Bronzewing mine of Great Central Mines (NASDAQ) which recently entered production.

Situated in the Yandal gold belt, 400 km north of the historic mining town of Kalgoorlie, Bronzewing is a large deposit by Aussie standards; the contained resource is estimated at 93.3 million grams (3 million oz.). Reserves of 20.4 million tonnes grading 4.6 grams gold per tonne (uncut) have been outlined in four separate deposits. In addition, appreciable gold values exist in overlying laterites.

Based on existing reserves in the probable category, a mine life of eight years is estimated, and management is confident that new ore will be uncovered. Initially, Bronzewing, which cost $63.9 million to develop, will yield 6.2 million grams (200,000 oz.) per year. Three open cuts are providing feed for the mill.

The orebody was discovered despite its having been totally obscured by deep, transported alluvials and a thick layer of leached clays to depths of about 90 metres. Few Australian companies would have been willing to incur the drilling costs required to delineate the deposit, where fresh rock is encountered below 120 metres.

The Bronzewing story began in 1991 when Great Central acquired tenements in the region from a prospector. Drilling had to be abandoned because of heavy rainfall, but a later re-evaluation brought the program back to life and the discovery was subsequently made on one of the last holes.

Some 110,000 metres were drilled within a 1.5-sq.-km area, and five rigs continue to work the property.

Gold at Bronzewing is associated with a dense stockwork of quartz veining, alteration of the host basalts, dolerites and felsic porphyries; it is accompanied by pyrite, pyrrohite and minor chalopyrite and scheelite. Free gold is often evident in drill core and drill cuttings; the deepest economic intersection to date is at 550 metres.

Meanwhile, Great Central has been exploring a new discovery along the Yandal belt, 120 metres to the north. Drilling to date has uncovered a preliminary reserve estimate of 10.5 million tonnes grading 3 grams (uncut) at the Jundee property, where a feasibility study is due for completion later this year.