Demonstrated reserves — A collective term for the sum of coal in both measured and indicated resources and reserves. Deposit — Mineral deposit or ore deposit is used to designate a natural occurrence of a useful mineral, or an ore, in sufficient extent and degree of concentration to invite exploitation.
Right: An illustration of a Baghdad battery from museum artifact pictures. (Ironie/Wikimedia Commons) Clay jars with asphalt stoppers and iron rods made some 2,000 years ago have been proven capable of generating more than a volt of electricity.
Underground hard rock mining refers to various underground mining techniques used to excavate hard minerals, usually those containing metals such as ore containing gold, silver, iron, copper, zinc, nickel, tin and lead, but also involves using the same techniques for excavating ores of gems such as diamonds.
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Coal mining - Choosing a mining method: The various methods of mining a coal seam can be classified under two headings, surface mining and underground mining. Surface and underground coal mining are broad activities that incorporate numerous variations in equipment and methods, and the choice of which method to use in extracting a coal seam ...