Mining giant Rio Tinto said it has unearthed a "remarkable" 12.76 carat pink diamond in Australia, the largest of the rare and precious stones ever found in the resources-rich nation.

Named the Argyle Pink Jubilee, the huge rough stone was found at Rio's pink diamond operations in the Kimberley region of Western Australia and would take 10 days to cut and polish, the miner said on Wednesday.

The New South Wales State Library in Australia launched a "search and rescue" mission on Friday to revive lost indigenous languages, using the letters and diaries of early British settlers.

When the British first arrived on the shores of what became Sydney Harbour in 1788, an estimated 250 local languages were spoken in Australia, but many have been lost.