Metamorphic rock is formed underground through a process that changes a rock's molecular structure due to pressure, heat and chemical reactions. A metamorphic rock forms from a parent rock called a protolith. Depending on conditions, a protolith can transform into any metamorphic rock. Because protoliths are capable of undergoing vast changes, identifying them is sometimes difficult for geologists.
Under extreme pressures, such as between two colliding tectonic plates, the minerals of a metamorphic rock group together and align to form foliation, which appears as stripes in the rock. One example of a heavily foliated rock is gneiss.
Alternatively, highly heated areas, such as near magma chambers, produce vastly different metamorphic rocks. One example is hornfels.
Another area for metamorphism is at a subduction zone where oceanic plates collide with and bend under continental plates. Because these high-pressure areas are near the ocean, they are cooler and produce different metamorphic results. One example of this is the creation of a blue mineral called glaucophane. This mineral in the rock foliates from high pressure and creates blueschist, a blue-tinted version of schist.
A protolith may change a number of times before reaching its final metamorphic stage. For example, gneiss may begin as shale that turns into slate, phyllite, schist and finally gneiss.Learn More
The specific type of rock that forms when magma cools at the Earth's surface is extrusive igneous rock. Igneous rock forms when magma cools, but where the magma cools determines the type of igneous rock that forms. Igneous rock gets its name from the Greek word for fire and is so called due to the extremely hot liquid from which the rocks originate.Full Answer >
A metamorphic rock that's formed from shale is slate. Slate is a low-grade rock that's used as a building material. It is often used for roofing tile because of the ease with which it can be split into thin sheets. If slate is installed properly, it's also waterproof.Full Answer >
The molecular structure of a diamond makes it hard, as diamonds are comprised of carbon atoms linked closely together in a lattice structure. The atoms are linked tightly via covalent bonds wherein two atoms share an electron. A tetrahedral unit is composed of five carbon atoms, with one carbon atom sharing electrons with the other four. An extremely strong molecule is formed from the tetrahedral bonding of five carbon atoms.Full Answer >
Metamorphic rocks are formed when the properties of existing igneous or sedimentary rocks are altered by contact with heat or pressure. They are typically found deep underground where the conditions necessary for their formation exist.Full Answer >