Consideration of samples from the large range of ore samples analysed as part of the OSNACA (Ore Samples Normalised to Average Crustal Abundance: http://www.cet.edu.au/projects/osnaca-ore-samples-normalised-to-average-crustal-abundance) analytical program at the Centre for Exploration Targeting at the University of Western Australia and as certified reference materials by ORE Research & Exploration Pty Ltd ( http://ore.com.au) indicates that some Australian ores have potential as sources for critical commodities as by-products or 'companion metals'. Komatiite-hosted nickel sulfide and related deposits currently produce both platinum-group elements (PGEs) and Co as by products, but PGEs are also known to be present in unconformity-related uranium deposits and some porphyry Cu deposits, and Co is known but not recovered in some sediment-hosted copper deposits. The data suggest some potential for recovery of PGEs as companion metals, although at present time such recovery is not economic.

Although Mo and Re are not currently produced in Australia, there are a number of potential sources of these metals, including deposits in which molybdenite is recovered as the main commodity (e.g. porphyry Mo-Cu and skarn deposits) and others in which these metals could be recovered as by-products (e.g. porphyry Cu deposits and sediment-hosted deposits of various kinds). As Mo and Re are commonly recovered as by-products from porphyry Cu deposits around the world, these deposits are perhaps the best potential source of Mo and Re as companion metals in Australia.

Pegmatite deposits in Western Australia and the Northern Territory, which are presently being assessed as Li resources, have potential for by-product Ta and Sn. The Toongi zirconia project in New South Wales, if developed, would recover Ta along with other metals including Hf, Nb, Y and rare earth elements (REEs). Although not currently recovered, the Olympic Dam and Prominent Hill iron oxide coper-gold (IOCG) deposits contain highly anomalous REE grades, with the Olympic Dam deposit having the second largest resource (after Bayan Obo) of these metals in the world.

At present, sphalerite (Zn) concentrates are an important source of Cd, Ga, Ge and In, with Cd currently being recovered by Australian Zn smelters. Although Cd concentrations are mostly a function of Zn grade, the concentrations of Ga, Ge and In depend strongly on deposit type, and the highest grades of Ga and In are from ores in which Zn is not the major commodity. The highest concentrations of Ga and In in Zn-rich ores are from deposits formed from higher temperature ore fluids, and include, for example, volcanic-hosted massive sulfide (VHMS) ores. In contrast, the highest concentrations of Ge are from deposits formed by low temperature, oxidised fluids such as Mississippi Valley-type deposits and siliciclastic-carbonate sediment-hosted Zn-Pb deposits (e.g. Mount Isa and McArthur River).

However, the highest concentrations of Ga and In are not from Zn-rich deposits, but from intrusion-related deposits. Gallium is most highly enriched in intrusion-related W ores and the Mount Weld REE-rich carbonatite, but extraction of Ga from these types of ores in not presently feasible. The highest concentration of In in the samples analysed is from intrusion-related Sn deposits, where it closely correlates with Cu, indicating that chalcopyrite may be a repository. Like Ga, recovery of In from these ore is not presently feasible.

Antimony and Bi, although not recovered from sphalerite concentrates, are also enriched in Zn-rich deposits. Antimony can be enriched in a large range of Zn ores types, but the most likely Australian Sb sources are orogenic stibnite deposits in which Sb would be the main recovered commodity if mined. Recovery of Sb from Zn-rich ores is at present not viable, although these ores contain significant potential companion resources of Sb. Bismuth, on the other hand, can be recovered from a range of mill products, including Pb (galena) and Cu concentrates. Like Ga and In, Bi is enriched in higher temperature deposits including VHMS deposits and some granite-related deposits.

Selenium and Te are currently recovered from anodic slimes produced during electrolytic recovery of Cu, hence Cu-rich ores are the best sources of these elements. The greatest potential for Se recovery is from some IOCG deposits and Cu-rich VHMS deposits, which are also the most promising sources of Te. Other deposit types can contain elevated Se and Te, but given the constraints imposed by extraction technologies, these sources may not be economically viable.