Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors. read more
Metamorphic rocks are most often found in mountainous regions though they can be seen wherever there are signs of geological upheaval in an area. This type of rock is formed by the transformation of another rock type, a change that is usually triggered by tremendous heat, pressure or other violent phenomena. read more
Metamorphic rocks can be found at great depths within the Earth's crust, at the base of mountains, or in contact zones where plutonic intrusions have metamorphosed the host rock via high temperatures. Metamorphic rocks can indeed be found at great depths within the crust, but for a rockhound, finding them elsewhere is not a problem. read more
You can find metamorphic rocks where subduction zones have stopped or moved. There are metamorphic rocks throughout the california coast range as that was at one time a subduction zone, but is no longer. There are many metamorphic rocks where there has been a collision of continental crust, such as the Alps, the Himalayas, and the Appalachian range. read more