Mining techniques refer to the various methods used to extract valuable minerals or other geological materials from the earth. Common techniques include surface mining, where materials are removed from the earth's surface, and underground mining, which involves digging tunnels or shafts to reach deeper deposits. Each method is chosen based on factors like the type of material, location, and environmental impact. Another important technique is placer mining, which involves extracting minerals from riverbeds or beach sands. This method often uses water to separate heavier materials from lighter ones. Additionally, mountain top removal is a controversial technique that involves blasting off the tops of mountains to access coal seams, raising concerns about environmental degradation.