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Why is shale considered an igneous rock?

Best Answers

As everyone else has pointed out, shale is a sedimentary rock, so put it firmly in your column of sedimentary rock types. Even when shale and its close cousin, mudstone, contain particles of volcanic ash (as several deposits in Arizona do), it's still considered a sedimentary rock, because the process of formation defines it. read more

Shale is not an igneous rock. Simply, because it's not a result of magma/ lava crystallization. It's a sedimentary rock which composition is very fine grains of silt and clay size, subjected to compaction from the overlying rock layers turning it into the flaky shape. read more

Slate is not an igneous rock. Slate is a metamorphic rock created by the compression of shale or mudstone under relatively low temperatures and pressures caused by the building up of sedimentary layers above it. Igneous rock is formed through the cooling and solidification of magma or lava emitted by volcanoes. read more

Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud." This composition places shale in a category of sedimentary rocks known as "mudstones." Shale is distinguished from other mudstones because it is fissile and laminated. read more

Extrusive Rocks Extrusive igneous rocks solidify from molten material that flows over the earth’s surface (lava). Extrusive igneous rocks typically have a fine-grained texture (individual minerals are not visible unless magnified) because the lava cools rapidly when exposed to the atmosphere, preventing crystal growth. read more