On the Paragenetic Relations of Minerals. 355 



manganese minerals are pseudomorphous, and the iron 

 minerals are likewise rich in pseudomorphs. 



3. A certain simplicity in the substances contained in these 

 lodes is obvious. The reason has yet to be ascertained why 

 the more valuable metals are almost altogether wanting, 

 and why the lodes of other formations are poor in ore in the 

 neighbourhood of manganese iron lodes,Jas at Johanngeor- 

 genstadt ; and there is reason to believe that an examina- 

 tion of this phenomenon would lead to interesting results. 



XII. Fluo-barytic Formation. — This formation, when con- 

 sidered in conjunction with the minerals imbedded in it, is 

 certainly inferior to none in either technical or scientific in- 

 terest. For convenience sake, it will be better to overlook at 

 first the occurrence in it of useful ores, a proceeding which is 

 also justified by the fact, that many lodes of considerable 

 magnitude belonging to this formation are known, in which 

 no traces of either of those minerals have been found. 



The great distribution of the minerals constituting this 

 formation becomes more strikingly ' apparent, when it is re- 

 membered that they are found here and there, covering most 

 of the formations previously mentioned, and that they serve as 

 support for five of the following formations. It might indeed 

 be advantageous to class all the known lode formations as, 1, 

 Those older than the fluo-barytic ; 2, Those contemporaneous 

 with ; and 3, Those which are more recent than it. 



The two most important minerals of this formation are, as 

 its name indicates, fluorite and barytite. In most of the lodes 

 of this formation they may be regarded as constant associates. 

 However they do occur apart, and this is true more especially 

 of the barytite. 



The largest known lode of fluorite is that at Liebenstein 

 (Meiningen), called the Flossberg, and traversing zechstein. 

 Barytite lodes are often very large, for instance in Saxony, 

 and likewise very numerous. Miiller enumerates 1052 known 

 in the Erzgebirge through mining operations, and probably 

 this number is insignificant compared with that of the lodes 

 which are unknown. 



In some instances coclestine occurs together with barytite, 

 or as its substitute. 



