Sunday, June 11, 2017

Sapphire Mines In Australia

The mines of Australia have produced more commercial-grade blue sapphire than any other source in history.    The typical Australian sapphire is dark blue color with a strong green dichroism, and color zoning.  Many Australian sapphires are heat treated to lighten and improve their color and make them more transparent.  Beryllium treatments have also been used.  Crystals average about three carats in size.


Deposits are located in two main areas on the eastern part of the continent:  the gem fields at Anakie in Queensland, and the New England district of New South Wales.  After the late 1970s, sapphire production in Queensland declined as new sources were developed in Thailand and Madagascar.  However, there is recent, renewed interest in mining the area since the 2004 resolution of the Native Title Agreement. The Anakie gem fields are known for yellow and green sapphires in addition to the large quantities of blues.

New South Wales production is now at its lowest level in 40 years, although some untreated pink and orange stones have been seen in the market. Deposits at the New South Wales mines are extracted with backhoes and bulldozers. The gem gravel is covered by two to eighty feet of overburden, which is scraped away. Australia has strict environmental laws that require the reclamation of mined areas.