Mineralogist

The scientists whose primary documented field is the identification, classification or physical properties of minerals: Friedrich Mohs, Rene Just Hauy and Gustav Tschermak von Seysenegg among them, plus James Dwight Dana (author of the System of Mineralogy, the field's own standard reference, despite a Geologist co-label) and Abraham Gottlob Werner (founder of geognosy and an early systematic mineral classification, his defining historical role despite a Geologist co-label). Belongs here: a scientist whose primary contribution is mineral hardness, crystal structure, or a mineral classification scheme. Does not belong here: a scientist whose primary contribution is rock-forming process at a larger scale, held under Geologist instead.