Early Developments in Ore-Mineral Study

As there has been a very wide development within the field of ore mineral study during the last three or four decades, it seemed proper at this time to take stock of our knowledge and the important contributors to it. Any human historical document must be, in the very nature of things, somewhat incomplete. To give a brief outline of some of the developments in the study of ore minerals, start notice some of the developments.

In any chronological recording of events it is always impossible to give the final word except in terms of contemporary progress, and it is always difficult to say just when the particular process of reasoning that led to the establishment of a new branch of any science may have had its inception. Perhaps however, as a convenient sort of spring-board that we may use before diving into the subject proper, we may cite the observations on meteorites of Baron von Widmanstätten in 1809. While the famous figures bearing his name, which were later noted on metals also, were not observed in the first instance on minerals and not under the microscope, nevertheless they must have been studied under reflected light from a polished surface and so may be considered as a sort of stepfather of this branch of our science. Although noted at this time by Widmanstätten, the first published mention of these figures was made in 1812 by K. A. Neumann, who developed them on polished sections of the Elbogen meteorite by etching with nitric acid. Next we have Berzelius, polishing a surface of pyrrhotite and noting by macroscopic methods the presence of another mineral, probably pentlandite, which cut across it in the form of narrow veinlets. But, although other investigators, such as Chladni and Von Schreibers, continued the macroscopic study of meteorites, it was not until the time of Sorby, that any very substantial advance was made in this particular direction. Sorby, as you all know, was the first to develop the use of the petrographic microscope for the study of rock-forming minerals in thin sections. Inspired by this very notable contribution, this eminent investigator turned his attention also to the microscopic study of iron meteorites, using for this purpose polished sections of this extra-terrestrial material. A natural step was the use of this reflected-light method for the study of metals and alloys (1887), and so he was also largely responsible for the birth of the sister subject of metallography. But, while this method of studying polished surfaces under the microscope has been available since about 1865, it was not until twenty years later that it was applied to the study of ore minerals. At that time Baumhauer examined macroscopically polished sections of copper minerals from Chloride, New Mexico, using concentrated nitric and hydrochloric acids as etch reagents to differentiate the various minerals. The following year the same investigator applied this method to the study of smaltite-chloanthite ores from four German localities. From this time until the end of the last century there seems to have followed a fourteen year period when this method was very little used, and interest in it during that time was kept alive only by the work of such scientists as Becke during 1886, Drude during 1888-1890, Weinschenk during 1890, and Beijerinck during 1897-1898.