When used as an alloying element, antimony greatly increases the hardness and mechanical strength of lead. The main use of antimony is to harden lead in storage batteries, and it is increasingly being used in the semiconductor industry.
Historically and economically, antimony is the second most important metallic commodity in Victoria, after gold. The only significant ore mineral of antimony, stibnite (Sb2S3), is widespread as an accessory mineral in gold-bearing quartz veins, particularly in veins that intersect the Silurian – Early Devonian Murrindindi Supergroup sedimentary rocks of the Melbourne Zone.
Deposits are mostly in the form of reefs, shear lodes and fissure fillings, close to the hinge zones of folds within sediments, or associated with dykes. Stibnite is at economic concentrations at a few localities and in some veins there is more stibnite than quartz.
The sediment-hosted antimony deposits are epithermal, formed from hydrothermal solutions related to deformation of the Palaeozoic rocks. Although stibnite is a significant component of most gold ores within the Melbourne Zone, it has usually been discarded as waste.
Stibnite is also a minor constituent of gold-bearing sulphide reefs of the Bendigo Zone and there is bournonite (PbCuSbS3) in the silver–lead ores of eastern Victoria. Deposits at Costerfield, Ringwood and Coimadai account for 98% of the total recorded Victorian antimony production of about 24,500 tonnes.
- Minerals of Victoria - Geological Survey of Victoria Report 92
- Victoria's Minerals, Petroleum and Extractive Industries - Statistical Review
- Geology of Victoria - Geological Society of Australia