Geology
Lignite is geologically younger than higher-grade coals, originating mainly in the Tertiary period.
The Latrobe Valley in the state of Victoria, Australia contains estimated reserves of some 65 billion tonnes of brown coal. The deposit is equivalent to 25% of known world reserves. The coal seams are up to 100 metres thick, with multiple coal seams often giving virtually continuous brown coal thickness of up to 230 metres. Seams are covered by very little overburden (10 to 20 metres).
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