How gold ore is mined
Because gold is soft and heavy, a stream of water can separate it from gravel with no chemistry at all.
- stations
- 4
- things downstream
- 40
The short version
Gold is recovered two ways. Placer mines work loose gravel in river beds, where gold has settled because it is far heavier than the sand around it, and water carries the light material away. Hard-rock mines crush gold-bearing rock, and most of it is then dissolved out with a cyanide solution.
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Dig rock or gravel
Conventional mines remove gold-bearing rock from pits or tunnels. Placer mines instead work loose river gravel, the kind of ground the Klondike and Australian gold rushes were fought over.
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Screen out the boulders
Large commercial placer operations run gravel through rotating screens called trommels, which throw out boulders and cobbles. Hard rock is crushed to free the gold from the stone around it.
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Let gravity sort it
Gravel flows through a sluice box with ridges across its floor. Heavier particles sink and lodge behind the ridges while lighter sand is carried off downstream. Jigs do the same job by pulsing water through a bed of material.
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Dissolve it from the powder
Most hard-rock gold is recovered by cyanidation, introduced in the late 1800s. A cyanide solution forms a stable complex with the gold, pulling it out of the crushed ore. The method is highly toxic, so the water has to be tightly managed.
Worth repeating
- Gold mining dates back to at least 4700 BC.
- The Australian gold rushes began in 1851 when Edward Hargraves discovered gold near Bathurst, New South Wales.
- Cyanide forms such stable complexes with gold that it became the dominant way to recover it, from the late 1800s on.
Where it comes from
Gold mined in the latest year given in the Gold mining article; world production was 3,612 tonnes in 2022.
Where it goes next
Gold ore feeds 1 line directly and reaches 40 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How gold ore is mined." Assembly Line, 2026-11-03. https://assemblyline.org/make/gold-ore