The Western A Lode (WAL), an extension of the zinc -rich A lode at Broken Hill, NSW, shows a gradation between mnganese silicate -rich sulphide ores and the pelitic inetasedinients of the wallrocks. This sequence can be subdivided petrographically into four broad zones, approximately syinrrBtric about the centre of the lode. Passing from the pelitic wallrocks these zones are: a sillimanite gneiss, a gahnite -rich zone, a garnet quartzite and an amphibole -pyroxenoid zone. This latter zone may

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... further subdivided into amphibole and pyroxenoid subzones. Sulphides occur throughout the WAL sequence, and commonly are concentrated in the gahnite -rich zone and in the lower garnet quartzite, stratigraphically immediately below the lower amphibole subzone, but the principal concentration is in the pyroxenoid subzone. Distinct geochemical trends parallel the mineralogical variations: approaching the centre of the WAL from the wallrocks there is a distinct