His contemporary Abū Rayhān al-Bīrūnī also introduced an early scientific method in nearly every field of inquiry he studied. For example, in his treatise on mineralogy, "Kitab al-Jamahir" ("Book of Precious Stones"), he is "the most exact of experimental scientists", while in the introduction to his study of India, he declares that "to execute our project, it has not been possible to follow the geometric method" and develops comparative sociology as a scientific method in the field. He was also responsible for introducing the experimental method into mechanics, the first to conduct elaborate experiments related to astronomical phenomena, and a pioneer of experimental psychology.