What is shale?
Q: What is shale?
A: Shale is a type of fine-grained sedimentary rock that is formed from mud composed of clay minerals and tiny fragments of other minerals.
Q: What is the ratio of clay to other minerals in shale?
A: The ratio of clay to other minerals in shale varies.
Q: What is the characteristic feature of shale?
A: Shale is characterized by fissility, which refers to breaks along thin laminae or parallel layering less than one centimeter in thickness.
Q: What is the difference between shale and mudstones?
A: Mudstones are similar in composition to shale but do not exhibit fissility.
Q: How much organic matter do shales and mudrocks contain compared to other sedimentary rocks?
A: Shales and mudrocks contain approximately 95 percent of the organic matter found in all sedimentary rocks.
Q: What causes black shales to form?
A: Black shales form in anoxic conditions without oxygen, and they contain free carbon and iron sulfides such as pyrite, which give them their black coloration.
Q: How much organic matter do black shales contain by mass on average?
A: Despite containing a high percentage of the organic matter found in sedimentary rocks, black shales only contain less than one percent of organic matter by mass on average.
