corundum, sources.12, Australia.12, , gems

Ruby is rare in Australia, but in the Barrington area of New South Wales, ruby and pink sapphire form up to 50% by weight of the gem corundum concentrate. These stones have Cr₂O₃ contents of 0.60–1.42 wt.% and FeO contents of 0.44–0.75 wt.%. They typically range from 2 to 6 mm in size and contain inclusions of spinel and liquid-filled fractures. Polysynthetic twinning is common and is often associated with inclusions of boehmite needles. On the basis of trace-element content, the Barrington corundum is divided into two distinct suites: one related to ruby and the other typical of eastern Australian sapphires. The ruby-containing corundum suite originated in a metamorphic environment, whereas the non-ruby suite has a magmatic origin. Both suites were brought to the surface by basaltic volcanism.