UTAH ACADEMY OF SCIENCES 205 
analysis. The treatment of the ore, and the recovery 
and separation of the minerals into commercial pro- 
ducts are matters that in many instances can only be 
determined by experimental testing and research investi- 
gation. While the combined value of the minerals con- 
tained in an ore may make quite a respectable total yet 
the clean-cut separation of minerals from each other is 
extremely difficult. There are many causes for failure 
in the treatment of ores, some of which are perhaps un- 
avoidable, but as the underlying principles on which the 
science of ore dressing is founded deal not only with the 
chemical nature of the ores but also with their physical 
properties and characteristics, a thorough knowledge of 
these factors is essential to intelligent and. scientific 
concentration practice. 
Since in so many instances the successful treat- 
ment and recovery of the values in the ores depends on 
the physical condition of the minerals composing them 
it is of the utmost importance that this information be 
obtained and placed at the disposal of those engaged in 
experimental ore testing. The general character of the 
minerals in an ore may perhaps be deduced from the 
appearance of the material together with the information 
gained by a study of the chemical analysis but there is 
often no means available for checking up on the deduc- 
tions so formed without recourse to a visual examination 
of the ore itself by means of the microscope. Chemical 
analysis serves as an accurate and reliable method for 
ascertaining the percentage amounts in which the sev- 
eral elements exist in the material which is to be treated 
but it does not give the remotest clue to the manner in 
which the minerals, representing these values, are 
associated. In some ores the character of the constituent 
minerals is at once apparent from a casual examination, 
but ores in which the values exist in two or possibly three 
states of chemical combination it may be practically im- 
possible to determine the relative amounts of the various 
minerals except by microscopic examination. Even 
though the ore which is to be treated is known to contain 
all the value carrying minerals in the sulphide form 
there is no assurance that these minerals are associated 
in such a manner that their separation and recovery may 
