Shale is a soft, fissile sedimentary rock with layers of sand, mud, and clay. It comes in various colors and is used for manufacturing and as a source of fossil depositions. Oil shale is a blend of chemical compounds that can be used for energy but requires significant energy to extract.
Shale is a very common form of sedimentary rock found in deposits around the world. It is notable for being soft and highly fissile. Shale has numerous ornamental and practical uses, as well as being a rich source of fossil depositions that can provide insight into different eras of the Earth’s geological history.
This sedimentary rock begins as a deposition of sand, mud and clay, with very fine particles of other minerals such as quartz. Over time, the deposition slowly compresses, eventually turning into shale. One of the distinguishing features of this rock type are the layers of material that can be seen when the rock is cut crosswise, showing the successive layers of deposition that have occurred, with the rock tending to overhang or fracture along these deposits. The very fine grain of the particles is another distinguishing feature.
Shales come in a wide variety of colors. Some are so dark they are almost black, while others can be greenish, bluish, brown or cream, depending on the precise composition of the rock. In the case of fossil-bearing shales, the deposits form as a result of biological material that became trapped in the shale as it was deposited and subjected to pressure. In some cases, parts of the organism may be represented in mineralized form, while in others the rock contains only the impression of an organism which has decayed after the rock has begun to harden.
In manufacturing, shale is used as a filler material for concrete and brick. People sometimes confuse this rock with slate, a much harder rock that can be used for a wide variety of purposes including roofing, tile, chalkboards, and so on. In the case of slate, the rock is subject to metamorphic processes which modify the structure and properties of the rock, making it harder and more durable. While slate also has distinctive layers and tends to split along these layers when stressed, it is much harder than shale.
A type of rock known as “oil shale” is of interest to some people working in the energy field. Oil shale is not necessarily a shale, although it sometimes is, and it shares many of the traits associated with true shales. It carries a blend of chemical compounds that can be mined and used to generate energy. However, enormous energy is required to extract these compounds, making this rock attractive only in regions where other petroleum sources for energy have been depleted.
Protect your devices with Threat Protection by NordVPN
