Scheerer — Occurrence of Silver at Kongsberg. 19 



Fluor spar, and Quartz ; in places, however, these veins contain 

 native Silver in more or less quantity. From the mode of occurrence 

 it was thought possible to lay down the law, that Silver occurs only 

 where the veins cross Fall hands ; and sometimes this view was dis- 

 torted into — ^more or less Silver occurs everywhere where veins cross 

 Fall bands. The careful experience of the present day seems to 

 show that the following are the real circumstances of the case : — 



The impregnation with pyrites, on which the original idea of a 

 Fall band was founded, is not confined exclusively to one particular 

 bed, nor is it equal throughout one bed. All that can be said is that 

 a certain set of beds, for a considerable length and depth, is irregu- 

 larly impregnated with pyrites. This set of beds impregnated with 

 pyrites, which we will call a Fall hand zone, would be the proper ex- 

 tended notion of a Fall band, with the addition that within a Fall 

 band zone, beds of various kinds of schist may alternate with one 

 another. The occurrence of Silver where a vein crosses a Fall band 

 zone, does not depend on the enclosing rock containing pyrites, nor 

 upon its being a certain variety of schist. The above law has to be 

 extended into the fact, that where a vein crosses a Fall band zone 

 Silver occurs apparently in a quite irregular manner. 



Even this law, based upon experience, must not be accepted with- 

 out caution, in spite of its being so general. With regard to this, 

 the following questions may be asked : — 



Firstly. — Is it a well-asceitained fact that the Kongsberg veins 

 contain no Silver outside a Fall band zone ? 



Secondly. — Is it always possible to say, when driving a level, 

 whether one is within a Fall band zone or not ? On account of the 

 irregular and often very slight impregnation with pyrites, scarcely 

 or not at all visible, it must be Yery difficult in many cases to answer 

 this second question, and naturally this renders an answer to the 

 first still more uncertain. 



Thirdly. — Is it not possible that, besides the Fall band zones 

 visible above ground at day, and worked upon, or supposed to be 

 worked upon, there may exist other Fall band zones underground ? 

 Practically this question coincides with the first, and can only be 

 answered by following the veins beyond the borders of a Fall band 

 zone. 



By these considerations the miner sees himself deprived of the 

 sure basis of an old rule on which he had relied with confidence for 

 more than two centuries. Let us hope that the loss thus sustained 

 by the theory of veins will be richly compensated for by gain in 

 Silver in ground hitherto considered as barren. 



Besides this, in the above-mentioned report there is some further 

 information about the Kongsberg veins, of which the following was 

 specially mentioned : — 



In Christian's adit driven as far as the mine, " God's help in time 

 of need," to a length of nearly 2000 fathoms, 251 veins and strings 

 were cut. Of these, 84 (veins) are at least f -inch thick, 167 (strings) 

 possess a smaller thickness, some only as thick as a sheet of paper. 

 Of the 84: veins, 43 were till then unknown, 31 unexplored at this 



