Victoria
Under Victoria
Explorers in Victoria report their drilling to the State, usually when their licence ends, and the Geological Survey of Victoria keeps the holes in its Earth Resources borehole database. The part of it that covers mineral drilling, with the best gold and base metal assay in each hole, is open data.
That gives {holes} mineral drill holes you can see here. Nearly all were drilled by earlier explorers and by government boring parties, many of them long gone. This tour flies you through the places and stories behind them, then hands you the controls.
1870s to today
150 years of looking
Watch the holes arrive year by year, by the date each hole was drilled. The first ones are government bores from the 1870s to the 1910s, sunk to trace buried gold-bearing river gravels under the basalt plains. There are {d1900} holes from the 1900s alone.
Modern exploration then takes over: {d1980} holes from the 1980s and {d1990} from the 1990s. The 2020s look quiet ({d2020} so far) because recent drilling is mostly still confidential, and another {d0} holes have no usable date, so they only show when the year filter is open.
Gold
A gold State
Colour the holes by gold and the old goldfields of central and western Victoria light up. {Au} of the open-file holes were assayed for gold. Each column's height is the number of holes in it, and its colour is a high but typical grade there (9 in 10 of its holes are below it), so one lucky hole does not paint a whole district.
The belt from Stawell and St Arnaud through Ballarat, Maldon and Bendigo to Fosterville and Costerfield follows folded slate and sandstone cut by quartz reefs, the source of most of Victoria's gold.
1851
Ballarat
Victoria became a separate colony on 1 July 1851, and within weeks gold was found at Clunes, Buninyong and then Ballarat. The rush that followed made the colony's population grow about sevenfold within ten years. At Ballarat in December 1854 miners protesting against licence fees fought troops at the Eureka Stockade.
The early alluvial gold soon ran out at the surface and was followed underground and under the basalt. The holes here are coloured by gold. {site}
Deep leads
Creswick and the deep leads
North of Ballarat the old rivers that carried gold were buried by lava flows. Miners followed these 'deep leads' by shaft under the basalt, and the government drilled lines of bores to find where they ran. Many of the oldest holes on this map are those bores.
The holes here are coloured by gold where they were assayed. {site}
1851
Bendigo
Gold was found at Bendigo Creek late in 1851, and Bendigo grew into one of the richest reef goldfields in the world, with quartz reefs followed more than a kilometre underground. The last big mines closed in 1954.
In the 1990s and 2000s Bendigo Mining drilled deep holes under the city to test the reefs again. Most holes here carry no assay in the open file, so they show as plain points. {site}
1894
Fosterville
Gold was found at Fosterville, east of Bendigo, in 1894. In the 1970s and 1980s explorers drilled the oxidised rock near surface, and from the mid-2000s the mine went underground into sulphide ore. Around 2016 it hit the very high-grade Swan Zone, which made Fosterville one of the richest gold mines in the world for a time.
Most open-file holes here are from the early explorers, coloured by gold. Arsenic, which travels with the gold, shows the same trend. {site}
1869
Dunolly and the Welcome Stranger
In February 1869 John Deason and Richard Oates dug up the Welcome Stranger at Moliagul, near Dunolly. It is still the largest alluvial gold nugget ever found, with about 72 kilograms of gold.
The holes here are coloured by gold. {site}
1853
Stawell
Gold was found at Stawell in 1853. The Magdala mine, under the edge of the town, worked the deep ore from the 1980s until 2016, following a basalt dome down more than a kilometre.
Many of the holes here are mine drilling with no assays in the open file, so they show as plain points. {site}
Antimony
Costerfield
Costerfield, east of Heathcote, has been mined for antimony and gold since the 1860s. It is one of the few antimony producers outside China, and antimony is now on Australia's list of critical minerals.
Most of the holes here were drilled by the State's own Department of Mines in the 1970s. {site}
1862
Walhalla
In the steep valleys of Gippsland, Edward Stringer found gold at Walhalla in 1862. The Long Tunnel mine on Cohen's Reef was among the richest in Victoria until the early twentieth century.
Only a handful of modern holes test the old reefs. They are coloured by gold. {site}
1852
Beechworth and the Woolshed
Gold was found in the Ovens district in 1852, and the Woolshed Creek near Beechworth was one of the richest alluvial fields of the rush. It was worked by hand and later by sluicing and dredging.
Almost no open-file exploration holes sit here: the gold was in shallow creek gravels, worked long before drill rigs, and later explorers looked elsewhere.
Copper
Stavely: a buried porphyry belt
West of Ararat lie old volcanic rocks that formed in an ancient island arc, the kind of setting that hosts porphyry copper deposits. Pennzoil and North drilled here in the 1970s and 1980s, and the newer Thursday's Gossan and Cayley Lode finds came from the same ground.
The holes here are coloured by copper. {site}
Mineral sands
Mineral sands of the Murray Basin
Ancient beaches across the Wimmera and Murray Basin hold heavy minerals: zircon, rutile, ilmenite and rare earth minerals. They are found with short, closely spaced holes, which is why these fields look like dense grids. Iluka mined the Douglas deposits near Balmoral in the 2000s.
These holes have no metal assays in the open file, so they show as plain points. {site}
Your turn
How to read this map
Each point is one open-file hole, coloured by the best assay recorded for it in the element you pick. Victoria's open file carries only gold, silver, arsenic, copper, lead and zinc, and only for some holes. The assays are as companies reported them, with no quality checks, and most holes were drilled by earlier explorers, not by whoever holds the ground today. Treat it as history, not a resource.
Use Explore to pick an element, set a minimum grade, slide through the years, search for a company or place, and dive into 14 places in 3D.
