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The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Partial melting is the phenomenon that occurs when a rock is subjected to temperatures high enough to cause certain minerals to melt, but not all of them. Partial melting is an important part of the formation of all igneous rocks and some metamorphic rocks (e.g., migmatites), as evidenced by a multitude of geochemical, geophysical and petrological studies.
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
The melting temperature of dry granite at ambient pressure is 1215–1260 °C (2219–2300 °F); [13] it is strongly reduced in the presence of water, down to 650 °C at a few hundred megapascals of pressure. [14] Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present.
Niobium pentafluoride (NbF 5) is a white solid with a melting point of 79.0 °C and niobium pentachloride (NbCl 5) is yellow (see image at right) with a melting point of 203.4 °C. Both are hydrolyzed to give oxides and oxyhalides, such as NbOCl 3 .
For example, a mixture of anorthite and diopside, which are two of the predominant minerals in basalt, begins to melt at about 1274 °C. This is well below the melting temperatures of 1392 °C for pure diopside and 1553 °C for pure anorthite. The resulting melt is composed of about 43 wt% anorthite. [79]
Minerals with tin are almost always associated with granite rock, ... 0.7% copper, and 0.3% silver, with melting temperature of 217 °C (422.6 °F). [93]
The extraction of antimony from ores depends on the quality and composition of the ore. Most antimony is mined as the sulfide; lower-grade ores are concentrated by froth flotation, while higher-grade ores are heated to 500–600 °C, the temperature at which stibnite melts and separates from the gangue minerals.