"In August 1983 the first hole intersected 24m of massive...

"In August 1983 the first hole intersected 24m of massive sulphide in the Hellyer orebody.
By November 1984 approximately 22,000m of delineation drilling had been completed
and in June 1986 a 1.3km adit was driven to intersect the orebody. The Hellyer reserve
was defined as 16.9Mt @ 13.8% Zn, 7.2% Pb, 0.4% Cu, 167 g/t Ag and 2.5 g/t Au.
Production commenced in December 1986, using underground methods, with production
peaking at around 1.3mt pa until the orebody was mined out in June 2000. Material was processed at the newly constructed 1.3Mtpa Hellyer mill, purpose built to accommodate
the fine grinding necessary to liberate the sulphides via flotation."