This article documents how thermal manipulation is critical to the transformation of the earth’s raw materials into media and to maintaining those materials as media. Through an examination of thermal practices, including mineral extraction, the use of air-conditioning in media manufacturing and preservation, and thermal infrared imaging, thermal control is shown to be essential to the conversion of geological matter into circulations of media on a mass scale. In each of these cases, cultural assumptions and imperatives—the drive toward purity, the development of standardization, and the demand for homogeneity across elements and media objects—organize temperature management. The thermocultures of media inflect its composition, movements, and temporalities and embed it within existing regimes of capitalism, gender, race, and sexuality. The study of thermocultures offers an alternative to traditional infrastructural and geological analyses, one oriented less toward the excavation of elements from deep time and the depths of the earth and more toward the conditions in which geologic matter’s potentials are actualized as media. It also opens up a new set of genealogies for investigation, including the historical role of thermal management in the differentiation of gendered bodies.