Melting Points of Rocks
Igneous rocks form through the crystallization of magma. There is a considerable range of melting temperatures for different compositions of magma. All the silicates are molten at about 1200°C (when a part of rock) and all are solid when cooled to about 600°C. Often the silicates are grouped as high, medium and low-melting point solids.
The pattern shown above where different kinds of minerals crystallize at different temperatures is further developed in the Bowen reaction series. The crystallization temperatures play a large role in the development of the different kinds of igneous rocks upon the cooling of magma.
Different minerals, when together in the same rock, melt at much lower temperatures than individual minerals. The crystallization temperatures in this table are characteristic of the environment of rock that contains these minerals, as in magma beneath the Earth's surface. The melting temperatures of pure minerals may be quite different. For example, in the Bowen reaction series, quartz is crystallizing around 650°C, but pure quartz at one atmosphere pressure does not melt until about 1700°C. (See Quartz Wiki, 1670°C for β-tridymite and 1713°C for β-cristobalite)
Thanks to Dr. Dexter Perkins, Professor of Geology and Geological Engineering at the University of North Dakota, for comments on the dry melting temperatures of minerals:
Igneous rock concepts
Lutgens & Tarbuck