204 TRANSACTIONS OF THE 
THE USE OF THE MICROSCOPE IN 
ORE DRESSING* 
BY R. E. HEAD.1 
The microscope as an instrument for use in research 
work has long been recognized and its value in this capa- 
city has been established in many branches of scientific 
endeavor. As an example of one of the more recent applic- 
ations of the microscope in the field of research, the 
science of metallography or physical metallurgy is worthy 
of mention. This science is comparatively young, having 
been developed within the last fifty years, yet at the pres- 
ent time the use of the microscope as a means of observ- 
ing and assisting in the determination of the physical 
properties of metals and alloys has been adopted and used 
by scientists and manufacturers the world over. Its use as 
a means of studying the physical characteristics of rocks 
and minerals has been recognized by geologists as a 
source for obtaining information which would otherwise 
either remain unknown or require the use of devious 
and uncertain methods of investigation for its acquisition. 
The almost universal use of the microscope in these 
branches of research has been given much publicity in 
numerous papers that have appeared in the scientific 
journals, and in view of the fact that the problems 
encountered in the treatment of ores possess many fea- 
tures in common with those described in these writings, it 
appears strange that so little has been published con- 
cerning its application and use in ore dressing. 
The economic value of an ore deposit depends pri- 
marily both on the market price of its metallic content 
and also on the percentage of this value that can be 
recovered by general or special reduction processes. The 
metallic values may be readily ascertained by chemical 
*By permission of the Director, U. S. Bureau of Mines 
1Metallurgical Assistant, Intermountain Experiment Station of 
the U. S. Bureau of Mines, Salt Lake City, Utah. 
