88 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



other points in Prussia cinnabar occurs in veins traversing eruptive and 

 sedimentary rocks. These cases would lead one to suppose that cinnabar 

 occurs in much the same manner as other metallic sulphides. 



Austria. — TliG dcposlts of Idria were discovered during the closing 

 years of the fifteenth century. After a number of vicissitudes they passed 

 into the hands of the state and have been worked by the government for 

 public account ever since the year 1580. 



The geology of these mines is of great interest, for not only has it been 

 studied with the closest attention by highly competent geologists daily for 

 many years, but the occurrences are such as to throw much light upon the 

 nature of the deposit and the method of genesis. Mr. M. Y. Lipoid, as a 

 member of the Austrian Geological Survey, examined and mapped the 

 country surrounding the mines in 185G. In 18ii7 he took' charge of the 

 mines, and in 1874 published a memoir on the geology of the deposits and 

 of the surrounding region.^ In 1880 he wrote another paper upon the ore 

 deposits." From these memoirs the information given below is chiefly de- 

 rived. In 1878 Mr. Lipoid was good enough toacc.ompany me through the 

 mines under his charge. My stay was far too short to enable me to add 

 any original observations to those which the director had made ; but, since 

 his conclusions appear from the litei'ature not even yet to find entire accept- 

 ance, I may state that, to me, the presence of a fissure system such as Mr. 

 Lipoid described, and the direct dependence of the distribution of ore upon 

 this fissure system, seemed proved be3^ond question. 



The region surrounding Idria is composed of Carboniferous, Triassic, 

 and later rocks, which have been subjected to great disturbances. Of these 

 the chief is a compressive strain, the axis of which has a northwest and 

 southeast direction. This strain is manifested in part as a fold and partly 

 also by a dislocation. The faulting has taken place chiefly upon a single 

 northwest and southeast fissure, which, however, as is so usual, is accom- 

 panied by other fractures parallel to it. In the course of the faulting move- 

 ment a portion of the Carboniferous beds have been driven over the Triassic 

 strata, thus inverting the natural order. This fact formerly caused the age 



' Jahrbuch k. k. geol. Reichsaustalt, Wieu, vol. 24, 1874, p. 425. 

 -Das k. k. Quecksilberwerk zn Idria, 1881. 



