Question

why Metamorphic rocks are impermeable​

Answer 1

Answer:

Permeability is the ability of fluids to flow through rock. It depends on the connectivity of the pore space. Permeable rocks include sandstone and fractured igneous and metamorphic rocks and karst limestone. Impermeable rocks include shales and unfractured igneous and metamorphic rocks.

Answer 2

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For metamorphic rocks, this is because the metamorphic processes have completely obliterated the original porosity and permeability of the original rock, if any. For this reason, these low-permeability rocks are often used to store waste, including radioactive waste