contact metamorphism, on the other hand, may develop valuable mineral deposits (see pp. 20, 45-46).
Corundum is a product of contact metamorphism and also a result of direct crystallization from molten magma.
In contact metamorphism, thin sheets of molten rock produce less effect than thicker ones.
Garnets result mainly from contact metamorphism, and commonly occur either in schists and gneisses or in marble.
Lapis lazuli usually occurs in crystalline limestone, and seems to be a product of contact metamorphism.
Sapphire, ruby, emerald, and tourmaline result also from contact metamorphism of sediments in the vicinity of igneous rocks.
Hence it is that the subject of contact metamorphism is of interest to economic geologists.
contact metamorphism along both the quartz-porphyry and the diorite contacts was practically lacking.
|contact metamorphism |
A type of metamorphism in which the mineralogy and texture of a body of rock are changed by exposure to the pressure and extreme temperature associated with a body of intruding magma. Contact metamorphism often results in the formation of valuable minerals, such as garnet and emery, through the interaction of the hot magma with adjacent rock. See also aureole. Compare regional metamorphism.