Victoria is one of the richest gold provinces on Earth. Since the first discovery in 1851, the State has yielded about 80 million ounces (2500 tonnes), making up about 2% of all the gold ever mined throughout world history. It provided the foundation for the prosperity and population growth of Melbourne. The richest producers in Victoria were Bendigo (700 tonnes), Ballarat (400 tonnes) and Castlemaine-Chewton (130 tonnes). Victoria is still regarded as having significant potential for new gold mines.
What is Gold?
Gold is a naturally occurring, bright yellow metallic element. When pure, it has a density of 19.3 g/cm3 and is malleable. It is often found alloyed with silver, but in Victorian gold the silver content is generally less than about 5%. Victorian gold is said to have high fineness (mostly over 950, or about 23 carats).
Gold, Kaolin dyke, 12ft level, Golden Crown Mine, Yarrambat, Victoria.
Photographer: Frank Coffa / Source: Museum Victoria
Types of Gold
Primary gold in Victoria mostly occurs as grains and masses in reefs and veins of white quartz. There are thousands of these gold-bearing quartz reefs, from the west to the east of the State. Gold found in soil and stream beds, both young and old, is called alluvial or placer gold. All of it was originally from the quartz reefs. Alluvial gold comes in many shapes and sizes. Victoria is famous for giant masses of gold, known as nuggets, a few of which contained up to several thousand ounces of gold. Large nuggets can still be found using metal detectors on the long-abandoned goldfields.
Alluvial gold, shot, melon seed and cornet, Victoria.
Source: Museum Victoria
Where did gold come from?
Originally, the gold is thought to have been present in very old volcanic rocks buried deep beneath Victoria. During a period when the Earth’s crust was being heated and squeezed, the gold was sweated out of these rocks and dissolved in vast quantities of hot saline water. These salty solutions carried the dissolved gold up towards the surface (but probably not reaching it) through fractures and faults in the bedrock. Eventually, the solutions cooled sufficiently for the gold (and quartz) to crystallise out in whatever space was available.
Victorian geologists are still investigating when and how the gold was formed. Currently the evidence suggests not a single event, but several pulses between about 450 and 370 million years ago. Since then, millions of years of erosion have lowered the land surface, gradually exposing the gold-bearing quartz reefs to the weathering effects of the atmosphere. As the reefs broke up, the gold was released, firstly into the surrounding soil, then finally into nearby streams. From here it could be spread far and wide, often going through several cycles of transport and deposition.
Uses for Gold
While gold has several important uses (mainly in jewellery and in electronics), its main value comes from its use as an international money standard and tradeable commodity. Australia is one of the top five gold producers in the world, with most coming from Western Australia.
Weston, K. S. 1992. Minerals of Victoria. Geological Survey of Victoria Report 92.
Flett, James. 1970. The history of gold discovery in Victoria.
Stone, Douglas M. 2000. Gold Prospecting.