Rubis australasiens

Rubies occur in sporadic deposits across the continental exposures of Australiasia, although quite subordinate to sapphires, which are actively mined in a few gem fields. The main ruby finds are in alluvial placer deposits shed from Cenozoic basalt fields in eastern Australia, where corundum was brought up by eruptions as resistant crystals from underlying crustal and mantle sources. These rubies all show differences in inclusions, trace element signatures and oxygen isotope values reflecting origins from diverse metamorphic bodies. Barrington Tops rubies show intergrowths with sapphirine and Cr-bearing spinel and supplied a ruby mining venture. Cudgegong-Macquarie River Mg-rich high temperature rubies may represent diamond zone indicators. New England zoned rubies are unusual Ga-rich types, different to most rubies in general. Elsewhere, in central and western Australia, a few ruby finds are known in older metamorphic rocks. At Harts Range, ruby crystals in feldspathic lenses within deformed metamorphic schists and gneisses were worlced for cabochon and specimen material. At Holcitilca, South Island New Zealand, a unique rubyrich metamorphic rock is worlced for ornamental jewellery. Commercial ruby deposits are very limited in Australasia, however, the known ruby finds provide a scientific 'bonanza'.