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:RALS AND GEOLOGY 



up in ridge-like form above the surface of the ground. (2) St 

 werks. This term, borrowed from German miners, is used to denote 

 a series of usually narrow veins, ramifying amongst each other, and 

 uniting occasionally into bunches or pockets of ore. (3) Contact 

 veins. These are ordinary veins lying in immediate contact with 

 eruptive masses, or between two different kinds of rock. Very 

 frequently, for example, a band of metalliferous matter is ft und to 

 lie between the edge of a mass of granite or trap and the enclosing 

 stratified rock, in which case it is said to occur in the " contact 

 country" of the two. (4) Gash veins. These are simply surface 

 clefts or fissures of slight depth or extent. They are commonly 

 filled with galena, and differ usually if not always from ordinary 

 veins by the absence of veinstones properly so-called. In many cases 

 they form mere strings of metalliferous matter. Attempts have 

 been made to work deceptive veins of this character, in the townships- 

 of Eramosa, Clinton, and Mulmur. 



Mineral veins may also be arranged to some extent as regards 

 their structure or texture in five groups, as follows: (1) Compact 

 veins. In these, the fissure is filled entirely with a solid and more or 

 less uniform mass of ore. (2) Open ns. The fissure, in these 

 veins, is only partially occupied by mineral matter,' open spaces 

 occurring throughout the vein generally. Large cavities or " vugs," 

 often lined with fine crystallizations, occur here and there in veins 

 of various kinds ; but in these open veins, so-called, the insterstices 

 or free spaces are especially numerous. (3) Banded veins. These 

 are filled or lined with distinct bands or zones of different substances, 

 the bands of the two walls corresponding in character, as in the 

 annexed figure. The two outer 

 bands, or those against the walls, 

 may consist, for example, of 

 brown ferruginous gossan, the 

 two next of quartz, the two 

 within these, of copper pyrites, 

 succeeded by zinc blende, quartz, 

 calcspar, galena, or other sub- 

 stances, in regular, banded alter- 

 nations. Veins of this kind are 

 exceedingly abundant in many mining districts, but characteristic: 



