CLASSIFICATION OF ORE DEPOSITS. 369 



tific zeal or knowledge on the part of those who are practically engaged in 

 mining. The phenomena to be investigated must be studied in the under- 

 ground workings of mines, in which not only is a very small area open to 

 observation as compared with the surface phenomena on which other geo- 

 logical reasonings are mainly based, but they are not in their nature as 

 permanent as are the latter and soon become obscured by decay or entirely 

 inaccessible. But, while the attainable facts are thus relatively meager, 

 they have not all been made available to the student, for the reason that 

 those practically engaged in mining are too often content with noting those 

 alone which have an immediate practical bearing, and have neglected to 

 put on record those of merely theoretical interest, which, nevertheless, if 

 carefully observed, might afford a basis for scientific generalizations of great 

 economic importance. 



We can only hope to arrive at a satisfactory and rational classification, 

 which shall be founded essentially on genetic principles, when our knowl- 

 edge of ore deposits shall be vastly increased by the accumulation of a 

 great number of scientific observations, based on correct geological studies, 

 and towards this accumulation we must look to those practically conducting 

 mines for a most essential contribution, since they alone have the opportu- 

 nity of daily observation of the constantly changing phenomena which ore 

 deposits present. Meanwhile it may be of use to review some of the more 

 prominent systems of classification proposed by modern writers upon ore 

 deposits, and to consider their relative applicability to the important class 

 of deposits under consideration. 



As the Germans were the first to write upon mines and ore deposits 

 and the classifications adopted by other nations have been to a greater or less 

 degree founded upon their wt)rk, the first place will be given to a mention 

 of those most current in Germany at the present day. The original edition 

 of B. von Cotta's treatise upon ore deposits appeared in 1853, and has not 

 been essentially changed in the later edition here quoted. The next classi- 

 fication quoted is that of Dr. Joh. Grimm, professor of the School of Mines 

 in Pfibram, Bohemia. The third is that given in his course on mining at 

 the School of Mines of Berlin, by Professor H. Lottner, and published by his 



MON XII 24 



