Although considerable work has been undertaken by some prominent geologists, the best known of which is that of Paul Billingsley and J. A. Grimes\u27, in investigating the ore deposits of the Boulder Batholith and surrounding area, there has not been any complete microscopic investigation of these deposits, as a whole, published in the literature. With this in mind it was suggested to the writer by Professor Paul A. Schafer, of the Montana School of Mines, that a microscopic study of the ores of this region would be a worthwhile geologic problem.
It was thought that the mineral association and the mode of mineral occurrence might afford methods of classifying these deposits so that they could be correlated with the age relationships worked out by Billingsley and Grimes
