The principal objective of this research project is to quantify the relationships among melt bulk composition, temperature, and structure by using micro-Raman spectroscopy with a high-temperature heating stage. Laboratory experiments will be conducted on alkali and alkaline earth aluminosilicate melts at temperatures up to 1700oC. Results of the experiments will enable identification of the predominant structural units in the melt as a function of bulk composition and temperature, derivation of quantitative estimates of equilibrium constants, and computation of thermodynamic and transport properties. The results will be applied to the study of chemically complex natural magmatic liquids and will ultimately find application in elucidating the behavior of melts within and on the Earth's surface.