This web page is your entrance into theoretical igneous petrology. Theoretical petrology provides the tools for making quantitative estimates of the conditions that transpired during the processes that formed volcanic rocks. The conditions you want to estimate are pressures, temperatures, vapor pressures, and phase compositions. The processes you want to infer include internal interactions such as nucleation of minerals, formation of zoning patterns in minerals, changes in melt composition during crystallization, and the formation and composition of additional fluid phases. You also want to consider external interactions with the country rock, such as contamination of the magma by country rock or melting of country rocks due to heat released from the intruding melt.

The first step in the interpretive process is to discover the features of the rock suite that might provide the data you need to make interpretations. Next, you can constrain your interpretations by using methods based on the conservation of matter, followed by methods rooted in conservation of energy. Interpretations of flow patterns, rates of eruption and shapes of volcanic features are often based on methods derived from the conservation of momentum. When writing papers and reports about suites of volcanic rocks, you have to apply rock names. Many people do this first. I suggest you do it last for two reasons. First, naming rocks is boring, frustrating, and often acrimonious. Second, and more important, you can do a better job of naming rocks after you are as fully informed about their nature and origin as possible.