This mineralogical study, published in 1853 by Darwin's German contemporary Wolfgang Sartorius von Waltershausen (1809 76) illustrates the author's dedication to interdisciplinary research and his desire for greater scientific rigour in geology. Seeking to understand the formation of palagonite, a mineral commonly found in rocks produced by submarine eruptions, Waltershausen realised he would also need to understand the precise composition of another class of minerals, the feldspars, on which Robert Bunsen, also at Gottingen, was working independently. Building on his earlier fieldwork,...