326 The Paragenetic Relations of Minerals. 



having been formed at the same time and under the same 

 conditions, it may be inferred that they do not belong to one 

 species. In the same manner antholite, anthophylite, and a 

 dark green hornblende, with their characteristic peculiari- 

 ties, occur in immediate contiguity at Kienrud in Norway. 



In relation to mining, Professor Breithaupt is of opinion 

 that the study of the phenomena of paragenesis will be of 

 great importance by leading to a knowledge of the condi- 

 tions, under which the ores of the useful metals occur, so as 

 eventually to do away with the element of chance, or the 

 reliance upon mere empirical rules, and to substitute in 

 their place a scientific system of mining operations. Al- 

 though, as he admits, this result is undoubtedly very remote, 

 he considers it time that the by no means inconsiderable 

 number of known facts should be collected, systematised, 

 and their universality tested, in order to obtain some positive 

 basis for its future achievement. One of the most import- 

 ant points in such an undertaking, is the progressive 

 development of one inorganic mass from another — the 

 accurate determination of relations of date, both as regards 

 geological formations and individual minerals. He expresses 

 his conviction, that as observation extends, it will become 

 more obvious that the association of minerals has its defi- 

 nite laws — that there exists, so to speak, a certain economy 

 of inorganic nature, whose investigation will be no less 

 attractive than practically useful. It will then be seen 

 that the same uniformities of association present themselves 

 under very different circumstances, in mixed rocks, as well 

 as In isolated deposits, in vesicular cavities, as well as in 

 lodes. 



It is here necessary to call attention to the fact, that mine- 

 rals present two distinct kinds of structure — the crystalline 

 and the non-crystalline. Although in many compact amor- 

 phous minerals, the ultimate molecules may be crystalline 

 both in structure and form, there are others whose structure 

 is unquestionably of a different character, for instance, opal 

 and obsidian. Again, of the non-crystalline minerals there 

 are at least two classes, of which the above substances may 

 be taken as the types. Obsidian bears all the characters of 



