Historical information

It is not known where this opal originated. Common Opal is formed from silica-rich water entering the earths crust and hardening into a gel of water and silica-spheres, layered through the specimen. Common opal differs from precious opal in colouration and appearance, with precious opal including more colours, and having a translucent or glossy appearance, where common opal shows less colour and is typically opaque. It scores high on the Mohs hardness scale, and is common throughout the world, especially in Australia, where it is far more prevalent than the highly-prized precious opal. Australia is also the highest producer of opals in the modern world.


This specimen is part of a larger collection of geological and mineral specimens collected from around Australia (and some parts of the world) and donated to the Burke Museum between 1868-1880. A large percentage of these specimens were collected in Victoria as part of the Geological Survey of Victoria that begun in 1852 (in response to the Gold Rush) to study and map the geology of Victoria. Collecting geological specimens was an important part of mapping and understanding the scientific makeup of the earth. Many of these specimens were sent to research and collecting organisations across Australia, including the Burke Museum, to educate and encourage further study.

Physical description

A solid, silica-based mineral specimen of Common Opal in shades of grey, green, and yellow, with a thick grey vein running through the centre.