286 



chite and copper pyrites. These same metalli- 

 ferous situations are found also in Franconia in 

 the gruensteins of the mountains of Steben and 

 Lichtenberg. With respect to the geeen slates 

 of Malpasso, which bear all the characters of 

 transition slates, they are identical with those, 

 which Mr. von Buch has so well described, 

 near Schoenau in Silesia. They contain beds of 

 gruenstein, like the slates of the mountains of 

 Steben, which we have just mentioned % The 

 black limestone of the Morros de San Juan, is 

 also a transition limestone. It forms perhaps a 

 subordinate stratum in the slates of Malpasso. 

 This situation would be analogous to what is 

 observed in several parts of Switzerland-^ . The 

 slaty zone, the centre of which is the ravine of 

 Piedras Azules, appears divided into two for- 

 mations. On some points we think we observe 

 one passing into the other. The gruensteins, 

 which begin again to the South of these slates, 

 appear to me to differ little from those found 



* Buch, as above, vol. i, p. 75. On advancing into the 

 adit for draining the mine (Friedrich-Wilhelmstollen), which I 

 caused to be began inl794,near Steben, and which is yet only 

 340 toises long, in the transition slate have successively been 

 found subordinate strata of pure and porphyritic gruenstein, 

 strata of lydian stone and ainpelite (alaunsckiefer) , and strata 

 of fine grained gruenstein. All these strata characterize 

 the transition slates. 



f For instance at the Glyshorn, at the Col de Balme, &c. 



