4 4 KEMP'S ORE DEPOSITS. 



mere form is eliminated to the last degree, and well-recognized 

 geological phenomena are brought to the foreground. It has in- 

 deed been said with force that the origin of ore deposits is a sub- 

 ject which is very largely a matter of hypothesis, and that it in- 

 volves profound subterranean causes, of which we know but little. 

 Still, it is held that an acquaintance with what has been accom- 

 plished in recent years by our best workers, and a rigid adherence 

 to well-recognized principles in geology and mineralogy, especially 

 as developed in rock study (i.e., in that department of geology 

 that of late years we have grown to call petrography), will estab- 

 lish much that cannot be questioned, and will aid in differentiating 

 the cases which are still objects of reasonable doubt. It is, how- 

 ever, true that among the subjects on which human imagination, 

 often superstitious, has run to wild extremes, and on which cranky 

 dreamers have exercised their wits, the origin of ore deposits 

 stands out in particularly strong relief. 



1.06.04. A. Schemes Involving only the Classification of 

 Veins. 



(i) 



G. A. von Weissenbach 1 (Gangstudien, 1850, p. 12). 



(a) Sedimentargange (Sedimentary Veins). 



(b) Kontritionsgange (Attrition Veins). 



(c) Stalactitische oder Infiltration sgange (Stalactitic or In- 



filtration Veins). 



(d) Plutonische oder Gebirgsmassengange (Masses, dikes, 



knobs, bosses, etc., not necessarily with ores). 



(e) Ausscheidungsgange (Segregated Veins). 



(f) Erzgange (True or Fissure Veins). 



(2) 



B. von Cotta, in comments on Von Weissenbach's Scheme. 

 Gangstudien, 1850, p. 79. According to the vein 

 filling. 



1. Gesteinsgange (Dikes). 



(a) Not crystalline (Sandstone). 



(b) Crystalline (Granite). 



2. Mineralgange (Veins). 



(a) Of one non-metallic mineral. 



(b) Of several non-metallic minerals. 



3. Erzgange. Ore veins. 



1 See also Whitney's Metallic Wealth of the U. S., 1854, p. 44. 



