This dissertation is a contribution toward low pressure geochemistry and petrology of alkaline rocks. In order to analyze the phase equilibria in multiply saturated potassic alkaline systems, experiments were performed at one atmosphere pressure and under the $\rm f\sb{O2}\sim QFM$ buffer. Range of temperature covered in this study is 1060-1250$\sp\circ$C. In addition, temperature and composition dependency of low pressure mineral-melt equilibria involving olivine, pyroxenes, plagioclase, nepheline, and leucite were modeled using empirical equations.