VEINSTONES. 



modern ; appatite and some fluors being the oldest 

 of this description. Barytes seems one of the 

 newest substances which appear in veins. Quartz, 

 if not the most ancient, appears to be of all ages ; 

 while wacken and basalt seem to be recent. Trebra 

 has observed, that certain gangarts seem more 

 generally to be found in certain kinds of rock. 

 Quartz and barytes are more frequently found in 

 granite, than calcareous spar. Porphyry also 

 contains much quartz, little barytes, still less cal- 

 careous spar, and almost never fluor; but there 

 are gangarts of chalcedony and jasper, which are 

 seldom found in granite and gneiss. In argilla- 

 ceous mountains the prevailing gangart is calca- 

 reous spar, while barytes and quartz are rare. In 

 calcareous mountains quartz seldom occurs, while 

 calcareous spar, barytes, and fluor, are abundant. 



In the mines of Giromagny, in Alsace, the 

 chief gangarts are quartz, trap, fluor; the rock 

 being almost universally what was called petro- 

 silex, more probably hornstein than felsite. The 

 direction of the veins is very various ; and those 

 that are north and south sometimes have their 

 inclination to the east, sometimes to the west*. 

 Among veinstones must also be reckoned bricias, 

 composed of fragments of the mass of the veins, 



* See the table, Journ, des Mines, iv. 201. 



