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:

1. It is hard to generalize about the relation of melting temperatures of mafic vs felsic minerals in pure form relative to those in the Bowen series. For examples, see the discussion in Stack Exchange.
   很难概括基性矿物与酸性矿物在纯态下的熔点关系，与波文系列中的情况相比。例如，可参见Stack Exchange的讨论。
2. It is impossible to determine melting temps for micas, amphiboles and any other mineral that contains water - because hydrous minerals break down via dehydration reactions before they melt.
   无法确定石英、角闪石和任何含水矿物的熔点——因为含水矿物在熔化前会通过脱水反应分解。
3. And, we really cannot determine melting temperatures for minerals like quartz and Kspar because they change into different minerals when heated, before they melt, even though they do not contain water. (Melting temps for these minerals listed in tables are really the melting temps of high-temperature polymorphs.)
   然而，我们无法确定如石英和钾长石这样的矿物的熔点，因为它们在加热过程中会转变为其他矿物，即使它们不含水。（这些矿物在表中的熔点实际上是高温多形体的熔点。）
4. And, many minerals melt incongruently, so what is really the melting temperature? The eutectic, or the temp at which everything is molten?
   • "A eutectic system is a homogeneous, solid mixture of two or more substances that form a superlattice; the mixture either melts or solidifies at a lower temperature than the melting point of any of the individual substances."ThoughtCo
     一种共晶体系是两种或多种物质的均匀固态混合物，形成超晶格；这种混合物在比任何单一物质的熔点更低的温度下熔化或凝固。
   许多矿物是不规则熔融的，因此真正的熔融温度是什么？是共晶温度，还是一切物质都熔融的温度？
5. And, many melting temps in the literature are eutectic temps. For example if you google melting of muscovite, you will find that it always refers to melting of muscovite and quartz together.
   许多文献中的熔点实际上是共晶点。例如，如果你在谷歌中搜索石英的熔点，会发现它总是指石英和白云母共同熔化的温度。