Gold

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             The majority of gold mined in WA is found in a large area known as the Yilgarn Block. This area comprises narrow zones of folded and metamorphosed (changed by heat and pressure) sediments and volcanic rocks surrounded by granite and granite-gneiss. .
             Gold nuggets are derived from the break-up of exposed primary gold-rich veins, or 'grow' within the soil or weathered rock as gold is gradually deposited from the groundwater. .
             The biggest nugget from WA was found at Larkinville, near Widgiemooltha in 1931. It weighed 32.177 kg and was found just 45 cm below the surface.
             Gold Mining.
             Gold mining has come a long way from the single mine shaft plus panning and dryblowing of the original diggers. Most Western Australian gold is mined from large open cut pits or extensive underground operations. .
             Open cut projects are best suited to secondary gold deposits or primary gold near the surface. The soft, weathered rocks are easier to mine, need less or no blasting, meaning gold grades as low as two grams per tonne can be economic. .
             Underground mining is for ore bodies that extend below 300 metres from the surface and generally requires grades of at least four grams per tonne to be viable. Many open cut mines progress to underground techniques if the gold grade is sufficient and continuous lodes or ore-shoots are found. .
             Both underground and open cut projects require waste to be removed, ore to be blasted, loaded into trucks and taken to the crusher for the first stage in separating the gold from the waste material. .
             After production ceases, underground mines and open cut pits are secured against intrusion by people and animals. Processing areas and other work sites are cleared, recontoured and revegetated. .
             Waste dumps are recontoured to form low hills which are covered with fertile topsoil and planted with local native vegetation. The industry has developed considerable expertise in establishing native ecosystems in the harsh, arid environment of many gold producing areas.