頁岩, or shale, is a fine-grained sedimentary rock composed mainly of clay minerals and small amounts of organic matter. It forms from the compaction of silt and clay particles over millions of years, often in quiet water environments like lakes and river deltas. Shale can vary in color, typically appearing in shades of gray, brown, or black. This rock is significant in the energy sector because it can contain 天然氣 and 石油, which are extracted through techniques like hydraulic fracturing. Additionally, shale is used in the production of 陶瓷 and as a source of 頁岩氣, contributing to energy resources worldwide.