24 GEOLOGICAL MEMOIRS. 



On the Metalliferous Veins o/ Pribram, Bohemia. 

 By Prof. Reuss. 



[Proceedings Imp. Acad. Sciences Vienna, May 23, 1856.] 



In this paper the author communicated the general results of his 

 researches on the relative ages and the origin of the metalliferous 

 veins of Pribram* in Bohemia. These veins appear to form a system 

 of distinct vein-formations, partly of sedimentary origin. The oldest 

 belong to Prof. Breithaupt's "Zinciferous formation;" these are 

 succeeded by the " Plumbo-zinciferous " ; more recent formations, 

 such as the " Argentiferous," are only represented by isolated por- 

 tions. 



The great variety of minerals constituting the Pribram veins per- 

 mits of no doubt of their having been formed at distinctly different 

 periods. By a careful investigation, no less than tvt^enty-four of 

 these genetic periods were made out. Sulphuret of zinc, galena, 

 quartz, and carbonate of iron belong to the most remote of these 

 periods ; and the ascending series is closed by calc-spar and iron- 

 pyrites. Most of these minerals have been formed repeatedly at 

 different periods. Thus calc-spar reappears five times, iron-pyrites 

 four times, quartz three times, and galena, sulphuret of zinc (blende), 

 sulphate of barytes, magnesio-calc-spar (brown spar), &c., each twice. 

 The successive formations of the same mineral species are generally 

 so different in shape, mode of grouping, and colour, and sometimes 

 even in their chemical characters, that a somewhat practised eye may 

 distinguish them at first sight. 



There are also highly diversified pseudomorphoses, which are very 

 interesting and instructive as bearing witness to the chemical changes 

 undergone by some minerals from the action of successive agents. 

 Some species are the first link of a continuous series of successive 

 modifications ; thus the argentiferous and antimoniferous galena have 

 in the course of time given origin to steinmannite, grey sulphuret and 

 white oxide of antimony, native silver, carbonate and phosphate of 

 lead, &c. Grey sulphuret of antimony is the root from which by 

 successive modifications the red sulphuret of antimony, native anti- 

 mony, and the arseniuret of antimony have been derived. Iron-py- 

 rites, by its decomposition, has furnished materials for ferro-chlorite 

 (eisen-chlorite), acicular iron-ore (nadel-eisenerz), red oxide of iron, 

 &c. The sulphate of barytes, of the older formation, exhibits a series 

 of the most interesting decompositions. [Count M.] 



On some GASTEROPODAy*rom the Alpine Trias. 

 By Dr. M. Hoernes. 



[Proceedings Imp. Acad. Sciences Vienna, March 1856.] 



In this communication Dr. M. Hoernes described and illustrated — 

 1st, several fossil mollusca recently collected at Unterpetzen, near 



* See also M. Kleszcznski on the Mining District of Pribram, Quart. Journ. 

 Geol. Soc. vol. xi. part 2, Miscell. p. 40. 



