Historical information
According to the 1912 Department of Mines Bulletin of the Geological Survey of Victoria, basalt covers a considerable portion of the Macedon area including Mount Macedon. Basalt is the most common form of rock underlying the earth's surface and is found in three kinds of rock forming environments: ocean divergent boundaries, oceanic hotspots, and mantle plumes and hotspots beneath continents.
Significance
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 mass, geological specimen in shades of grey and white.
Hyalite is a colourless variety of opal. It occurs as globular and botryoidal masses and irregular crusts in volcanic and pegmatite environments where the silica deposits from the gas phase.
Basalt is dark in colour, fine-grained igneous rock composed of plagioclase and pyroxene minerals. It is commonly formed as an extrusive rock, such as lava flow. It is one of the most common forms of rock underlying the earth's surface.
