Petrology and cycles and the use of thermodynamic data and experiments in order to better understand the origins of rocks. There are three branches of petrology, corresponding to the three types of rocks: igneous, metamorphic, and sedimentary, and another dealing with experimental techniques: Petrology Petrology (from the Greek πέτρος, "pétros", "rock" and λόγος, "lógos", "subject matter", see -logy) is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and
What Is Art? What Is Art? What is Art? ( "Chto takoye iskusstvo?") is a book by Leo Tolstoy. It was completed in Russian in 1897 but first published in English due to difficulties with the Russian censors. Tolstoy cites the time, effort, public funds, and public respect spent on art and artists as well as the imprecision of general opinions on art as reason for writing the book. In his words, "it is difficult to say what is meant by art, and especially what is good, useful art, art for the sake of which we might condone such sacrifices as are being