65 Million Years Ago Towards the end of the Cretaceous period sea levels receded, dinosaurs became extinct & the vast desert sandstones were layed down which host Australia's National Treasure
30 Million Years Ago By the mid Tertiary period the process of Opalisation had begun
50,000 Years Ago Australian Aboriginal 'dreamtime' regards the birth of Opal as sacred
The Classical source of Opal is likely 'Anatolia' or modern Turkey, although India has oft been cited.
First literary record of 'Opal' by Ancient Greek scholar Theophrastos
79 AD Pliny the Elder describes Opal as a multi-coloured gem, refering to Nonius' stone and paste imitations of Opal in his Historia Naturalis
1100 AD First commercial Opal mines Olbayana Hungary.
Albertus Magnus exults the virtues of the Orphanus Opal set into the Crown of the Holy Roman Emperors
Bernardino De Sahagun describes a stone used and named by the Aztecs in his Florentine Codex
1597 Emperor Rudolf II issues the first Opal mining lease in Dubnick present day Slovakia
1840 First recorded discovery of Opal in Australia at Angaston S.A. by Professor Johann Menge (not a commercial deposit)
1851 Opal found by a peasant farmer near Querétaro Mexico
1869 Queensland’s first recorded Opal find at Listowel Downs near Adavale
1871 First Opal lease in Australia Pride of the Hills mine Toompine Queensland
Opal Miners Berkleman & Lambert attend the International Exhibition in London
1889 Light Opal discovered by Kangaroo hunters at White Cliffs NSW
1901 Tully Wollaston takes Boulder & White Opal to the Empire Exhibition in London
1902 Black Opal is found at Lightning Ridge NSW
1912 Opal proclaimed October birthstone by American National Association of Jewelers
1915 The world’s largest Opal deposits, found at Coober Pedy South Australia
1930 Andamooka, famous crystal Opal fields, discovered by boundary riders in SA
1930's The Fire Queen Opal stone is sold to J.D. Rockefeller fetching a record £75,000
1945 Opal found at Pedro II Piaui State in Brazil
1965 Scientists from Austalia's CSIRO discover the internal structure of Opal
Australia Post issued Opal Stamps on two occasions:
Firstly in 1974 an 8c stamp was part of a gemstone series.
Then in 1995 two denominations were issued depicting Australia's National Gemstone;
A Light Opal $1.20 and a Black Opal $2.50 stamp, Boulder Opal featured on the cover of the Stamp pack.
1990 Opal industry reaches historical peak worth $500m to Australian economy
Opal proclaimed Australia’s National Gemstone
1999 First National Opal Symposium held at Lightning Ridge NSW, now a biennial event
2008 Significant reserves and quality Opal discovered at Welo in Ethiopia
2008 Black Opal announced as the new Emblem of the State of New South Wales