Metamorphic rocks are formed from existing rocks that undergo changes due to heat, pressure, or chemical processes. These changes occur while the rock remains in a solid state, meaning it does not melt. Here are some key characteristics of metamorphic rocks:
- Texture: Metamorphic rocks often have a foliated texture, which means they have layers or bands of minerals. This is due to the pressure they undergo during formation. Non-foliated metamorphic rocks, like marble, do not have these layers.
- Mineral Composition: The minerals in metamorphic rocks can change during the metamorphic process. For example, clay minerals can transform into mica minerals under high pressure and temperature.
- Hardness: Metamorphic rocks are generally harder than the original rocks they were formed from. This is because the process of metamorphism often results in the growth of new, harder minerals.
- Density: These rocks are usually denser than their original forms due to the compression they undergo.
- Color: The color of metamorphic rocks can vary widely depending on the minerals present. For example, marble is often white, while schist can be green, black, or even red.
Understanding these characteristics can help in identifying metamorphic rocks and appreciating the complex processes that form them.